[FFmpeg-devel] [PATCH v7] VideoToolbox H.264 Encoder

Rick Kern kernrj at gmail.com
Mon Feb 29 16:14:17 CET 2016


Autodetected by default. Encode using -codec:v vtenc.

Signed-off-by: Rick Kern <kernrj at gmail.com>
---
 MAINTAINERS            |    1 +
 configure              |   19 +
 libavcodec/Makefile    |    1 +
 libavcodec/allcodecs.c |    1 +
 libavcodec/vtenc.c     | 1320 ++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 1342 insertions(+)
 create mode 100644 libavcodec/vtenc.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 155642b..650da3c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -289,6 +289,7 @@ Codecs:
   vp8                                   David Conrad, Jason Garrett-Glaser, Ronald Bultje
   vp9                                   Ronald Bultje, Clément Bœsch
   vqavideo.c                            Mike Melanson
+  vtenc.c                               Rick Kern
   wavpack.c                             Kostya Shishkov
   wmaprodec.c                           Sascha Sommer
   wmavoice.c                            Ronald S. Bultje
diff --git a/configure b/configure
index 8b7c423..97bb40f 100755
--- a/configure
+++ b/configure
@@ -289,6 +289,7 @@ External library support:
   --disable-sdl            disable sdl [autodetect]
   --disable-securetransport disable Secure Transport, needed for TLS support
                            on OSX if openssl and gnutls are not used [autodetect]
+  --disable-vtenc          disable VideoToolbox H.264 encoder [autodetect]
   --enable-x11grab         enable X11 grabbing (legacy) [no]
   --disable-xlib           disable xlib [autodetect]
   --disable-zlib           disable zlib [autodetect]
@@ -1509,6 +1510,7 @@ EXTERNAL_LIBRARY_LIST="
     schannel
     sdl
     securetransport
+    vtenc
     x11grab
     xlib
     zlib
@@ -2672,6 +2674,9 @@ libzvbi_teletext_decoder_deps="libzvbi"
 nvenc_encoder_deps="nvenc"
 nvenc_h264_encoder_deps="nvenc"
 nvenc_hevc_encoder_deps="nvenc"
+vtenc_encoder_deps="vtenc VideoToolbox_VideoToolbox_h pthreads"
+vtenc_encoder_select="bzlib zlib iconv"
+vtenc_encoder_extralibs="-framework CoreFoundation -framework VideoToolbox -framework CoreMedia"
 
 # demuxers / muxers
 ac3_demuxer_select="ac3_parser"
@@ -5687,6 +5692,20 @@ enabled openssl           && { use_pkg_config openssl openssl/ssl.h SSL_library_
                                check_lib openssl/ssl.h SSL_library_init -lssl -lcrypto -lws2_32 -lgdi32 ||
                                die "ERROR: openssl not found"; }
 enabled qtkit_indev      && { check_header_objcc QTKit/QTKit.h || disable qtkit_indev; }
+{ disabled vtenc_encoder && disable vtenc; } || 
+                            { disabled vtenc && 
+                              disable vtenc_encoder; } ||
+                            { enabled vtenc &&
+                              require VideoToolbox VideoToolbox/VTCompressionSession.h VTCompressionSessionPrepareToEncodeFrames -framework VideoToolbox &&
+                              enable vtenc_encoder; } ||
+                            { enabled vtenc_encoder &&
+                              check_lib VideoToolbox/VTCompressionSession.h VTCompressionSessionPrepareToEncodeFrames -framework VideoToolbox &&
+                              enable vtenc; } ||
+                            { disable vtenc && 
+                              disable vtenc_encoder; }
+enabled vtenc_encoder    && check_header "TargetConditionals.h" &&
+                            { check_cpp_condition "TargetConditionals.h" "TARGET_OS_MAC && !TARGET_OS_IPHONE" &&
+                              vtenc_encoder_extralibs+=" -framework VideoDecodeAcceleration"; }
 
 # libdc1394 check
 if enabled libdc1394; then
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 5389725..63fbb80 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -120,6 +120,7 @@ OBJS-$(CONFIG_TEXTUREDSPENC)           += texturedspenc.o
 OBJS-$(CONFIG_TPELDSP)                 += tpeldsp.o
 OBJS-$(CONFIG_VC1DSP)                  += vc1dsp.o
 OBJS-$(CONFIG_VIDEODSP)                += videodsp.o
+OBJS-$(CONFIG_VTENC)                   += vtenc.o
 OBJS-$(CONFIG_VP3DSP)                  += vp3dsp.o
 OBJS-$(CONFIG_VP56DSP)                 += vp56dsp.o
 OBJS-$(CONFIG_VP8DSP)                  += vp8dsp.o
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index 2097db0..29724bb 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -610,6 +610,7 @@ void avcodec_register_all(void)
     REGISTER_ENCODER(HEVC_QSV,          hevc_qsv);
     REGISTER_ENCODER(LIBKVAZAAR,        libkvazaar);
     REGISTER_ENCODER(MPEG2_QSV,         mpeg2_qsv);
+    REGISTER_ENCODER(VTENC,             vtenc);
 
     /* parsers */
     REGISTER_PARSER(AAC,                aac);
diff --git a/libavcodec/vtenc.c b/libavcodec/vtenc.c
new file mode 100644
index 0000000..7c6ebfb
--- /dev/null
+++ b/libavcodec/vtenc.c
@@ -0,0 +1,1320 @@
+/*
+ * copyright (c) 2015 Rick Kern <kernrj at gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <VideoToolbox/VideoToolbox.h>
+#include <CoreVideo/CoreVideo.h>
+#include <CoreMedia/CoreMedia.h>
+#include <TargetConditionals.h>
+#include <Availability.h>
+#include "avcodec.h"
+#include "libavutil/opt.h"
+#include "libavutil/avassert.h"
+#include "libavutil/atomic.h"
+#include "libavutil/avstring.h"
+#include "libavcodec/avcodec.h"
+#include "internal.h"
+#include <pthread.h>
+
+
+static const uint8_t start_code[] = { 0, 0, 0, 1 };
+
+typedef struct BufNode {
+    CMSampleBufferRef cm_buffer;
+    struct BufNode* next;
+    int error;
+} BufNode;
+
+typedef struct VTEncContext {
+    AVClass *class;
+    VTCompressionSessionRef session;
+
+    pthread_mutex_t lock;
+    pthread_cond_t  cv_sample_sent;
+
+    int async_error;
+
+    BufNode *q_head;
+    BufNode *q_tail;
+
+    int64_t frame_ct_out;
+    int64_t frame_ct_in;
+
+    int64_t first_pts;
+    int64_t dts_delta;
+
+    char *profile;
+    char *level;
+
+    bool flushing;
+    bool has_b_frames;
+    bool warned_color_range;
+} VTEncContext;
+
+static void set_async_error(VTEncContext *vtctx, int err)
+{
+    BufNode *info;
+
+    pthread_mutex_lock(&vtctx->lock);
+
+    vtctx->async_error = err;
+
+    info = vtctx->q_head;
+    vtctx->q_head = vtctx->q_tail = NULL;
+
+    while (info) {
+        BufNode *next = info->next;
+        CFRelease(info->cm_buffer);
+        free(info);
+        info = next;
+    }
+
+    pthread_mutex_unlock(&vtctx->lock);
+}
+
+static int vtenc_q_pop(VTEncContext *vtctx, bool wait, CMSampleBufferRef *buf)
+{
+    BufNode *info;
+
+    pthread_mutex_lock(&vtctx->lock);
+
+    if (vtctx->async_error) {
+        pthread_mutex_unlock(&vtctx->lock);
+        return vtctx->async_error;
+    }
+
+    if (vtctx->flushing && vtctx->frame_ct_in == vtctx->frame_ct_out) {
+        *buf = NULL;
+
+        pthread_mutex_unlock(&vtctx->lock);
+        return 0;
+    }
+
+    while (!vtctx->q_head && !vtctx->async_error && wait) {
+        pthread_cond_wait(&vtctx->cv_sample_sent, &vtctx->lock);
+    }
+
+    if (!vtctx->q_head) {
+        pthread_mutex_unlock(&vtctx->lock);
+        *buf = NULL;
+        return 0;
+    }
+
+    info = vtctx->q_head;
+    vtctx->q_head = vtctx->q_head->next;
+    if (!vtctx->q_head) {
+        vtctx->q_tail = NULL;
+    }
+
+    pthread_mutex_unlock(&vtctx->lock);
+
+    *buf = info->cm_buffer;
+    free(info);
+
+    vtctx->frame_ct_out++;
+
+    return 0;
+}
+
+static void vtenc_q_push(VTEncContext *vtctx, CMSampleBufferRef buffer)
+{
+    BufNode *info = av_malloc(sizeof(BufNode));
+    if (!info) {
+        set_async_error(vtctx, AVERROR(ENOMEM));
+        return;
+    }
+
+    CFRetain(buffer);
+    info->cm_buffer = buffer;
+    info->next = NULL;
+
+    pthread_mutex_lock(&vtctx->lock);
+    pthread_cond_signal(&vtctx->cv_sample_sent);
+
+    if (!vtctx->q_head) {
+        vtctx->q_head = info;
+    } else {
+        vtctx->q_tail->next = info;
+    }
+
+    vtctx->q_tail = info;
+
+    pthread_mutex_unlock(&vtctx->lock);
+}
+
+static CMVideoCodecType get_cm_codec_type(enum AVCodecID id)
+{
+    switch (id) {
+    case AV_CODEC_ID_H264: return kCMVideoCodecType_H264;
+    default:               return 0;
+    }
+}
+
+static void vtenc_free_block(void *opaque, uint8_t *data)
+{
+    CMBlockBufferRef block = opaque;
+    CFRelease(block);
+}
+
+/**
+ * Get the parameter sets from a CMSampleBufferRef.
+ * @param dst If *dst isn't NULL, the parameters are copied into existing
+ *            memory. *dst_size must be set accordingly when *dst != NULL.
+ *            If *dst is NULL, it will be allocated.
+ *            In all cases, *dst_size is set to the number of bytes used starting
+ *            at *dst.
+ */
+static int get_params_size(
+    AVCodecContext              *avctx,
+    CMVideoFormatDescriptionRef vid_fmt,
+    size_t                      *size)
+{
+    size_t total_size = 0;
+    size_t ps_count;
+    size_t i;
+    int status;
+    status = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(vid_fmt,
+                                                                0,
+                                                                NULL,
+                                                                NULL,
+                                                                &ps_count,
+                                                                NULL);
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error getting parameter set count: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    for(i = 0; i < ps_count; i++){
+        const uint8_t *ps;
+        size_t ps_size;
+        status = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(vid_fmt,
+                                                                    i,
+                                                                    &ps,
+                                                                    &ps_size,
+                                                                    NULL,
+                                                                    NULL);
+        if(status){
+            av_log(avctx, AV_LOG_ERROR, "Error getting parameter set size for index %zd: %d\n", i, status);
+            return AVERROR_EXTERNAL;
+        }
+
+        total_size += ps_size + sizeof(start_code);
+    }
+
+    *size = total_size;
+    return 0;
+}
+
+static int copy_param_sets(
+    AVCodecContext              *avctx,
+    CMVideoFormatDescriptionRef vid_fmt,
+    uint8_t                     *dst,
+    size_t                      dst_size)
+{
+    size_t ps_count;
+    int status;
+    size_t offset = 0;
+    size_t i;
+
+    status = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(vid_fmt,
+                                                                0,
+                                                                NULL,
+                                                                NULL,
+                                                                &ps_count,
+                                                                NULL);
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error getting parameter set count for copying: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    for (i = 0; i < ps_count; i++) {
+        const uint8_t *ps;
+        size_t ps_size;
+        size_t next_offset;
+
+        status = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(vid_fmt,
+                                                                    i,
+                                                                    &ps,
+                                                                    &ps_size,
+                                                                    NULL,
+                                                                    NULL);
+        if (status) {
+            av_log(avctx, AV_LOG_ERROR, "Error getting parameter set data for index %zd: %d\n", i, status);
+            return AVERROR_EXTERNAL;
+        }
+
+        next_offset = offset + sizeof(start_code) + ps_size;
+        if (dst_size < next_offset) {
+            av_log(avctx, AV_LOG_ERROR, "Error: buffer too small for parameter sets.\n");
+            return AVERROR_BUFFER_TOO_SMALL;
+        }
+
+        memcpy(dst + offset, start_code, sizeof(start_code));
+        offset += sizeof(start_code);
+
+        memcpy(dst + offset, ps, ps_size);
+        offset = next_offset;
+    }
+
+    return 0;
+}
+
+static int set_extradata(AVCodecContext *avctx, CMSampleBufferRef sample_buffer)
+{
+    CMVideoFormatDescriptionRef vid_fmt;
+    size_t total_size;
+    int status;
+
+    vid_fmt = CMSampleBufferGetFormatDescription(sample_buffer);
+    if (!vid_fmt) {
+        av_log(avctx, AV_LOG_ERROR, "No video format.\n");
+        return AVERROR_EXTERNAL;
+    }
+
+    status = get_params_size(avctx, vid_fmt, &total_size);
+    if (status) {
+        CFRelease(vid_fmt);
+        av_log(avctx, AV_LOG_ERROR, "Could not get parameter sets.\n");
+        return status;
+    }
+
+    avctx->extradata = av_malloc(total_size);
+    if (!avctx->extradata) {
+        CFRelease(vid_fmt);
+        return AVERROR(ENOMEM);
+    }
+    avctx->extradata_size = total_size;
+
+    status = copy_param_sets(avctx, vid_fmt, avctx->extradata, total_size);
+    CFRelease(vid_fmt);
+
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Could not copy param sets.\n");
+        return status;
+    }
+
+    return 0;
+}
+
+static void vtenc_output_callback(
+    void *CM_NULLABLE ctx,
+    void *sourceFrameCtx,
+    OSStatus status,
+    VTEncodeInfoFlags flags,
+    CM_NULLABLE CMSampleBufferRef sample_buffer)
+{
+    AVCodecContext *avctx = ctx;
+    VTEncContext   *vtctx = avctx->priv_data;
+
+    if (vtctx->async_error) {
+        if(sample_buffer) CFRelease(sample_buffer);
+        return;
+    }
+
+    if (status || !sample_buffer) {
+        av_log(avctx, AV_LOG_ERROR, "Error encoding frame: %d\n", (int)status);
+        set_async_error(vtctx, AVERROR_EXTERNAL);
+        return;
+    }
+
+    if (!avctx->extradata && (avctx->flags & AV_CODEC_FLAG_GLOBAL_HEADER)) {
+        int set_status = set_extradata(avctx, sample_buffer);
+        if (set_status) {
+            set_async_error(vtctx, set_status);
+            return;
+        }
+    }
+
+    vtenc_q_push(vtctx, sample_buffer);
+}
+
+static int get_length_code_size(
+    AVCodecContext    *avctx,
+    CMSampleBufferRef sample_buffer,
+    size_t            *size)
+{
+    CMVideoFormatDescriptionRef vid_fmt;
+    int isize;
+    int status;
+
+    vid_fmt = CMSampleBufferGetFormatDescription(sample_buffer);
+    if (!vid_fmt) {
+        av_log(avctx, AV_LOG_ERROR, "Error getting buffer format description.\n");
+        return AVERROR_EXTERNAL;
+    }
+
+    status = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(vid_fmt,
+                                                                0,
+                                                                NULL,
+                                                                NULL,
+                                                                NULL,
+                                                                &isize);
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error getting length code size: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    *size = isize;
+    return 0;
+}
+
+/*
+ * Returns true on success.
+ *
+ * If profile_level_val is NULL and this method returns true, don't specify the
+ * profile/level to the encoder.
+ */
+static bool get_vt_profile_level(AVCodecContext *avctx,
+                                 CFStringRef    *profile_level_val)
+{
+    VTEncContext *vtctx = avctx->priv_data;
+
+    const char *profile = vtctx->profile;
+    const char *level   = vtctx->level ? vtctx->level : "auto";
+
+    if (!profile && av_strcasecmp(level, "auto")) {
+        //Need to pick a profile if level is not auto-selected.
+        profile = vtctx->has_b_frames ? "main" : "baseline";
+    }
+
+    //Fewer cases for if-blocks below
+    if      (!strcmp("3", level)) level = "3.0";
+    else if (!strcmp("4", level)) level = "4.0";
+    else if (!strcmp("5", level)) level = "5.0";
+    else if (!av_strcasecmp("auto", level)) level = "auto";
+
+    *profile_level_val = NULL;
+
+    if (!profile) {
+        //VideoToolbox auto-selects profile and level.
+        return true;
+    } else if (!av_strcasecmp("baseline", profile)) {
+        if      (!strcmp("auto", level)) *profile_level_val = kVTProfileLevel_H264_Baseline_AutoLevel;
+        else if (!strcmp("1.3",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_1_3;
+        else if (!strcmp("3.0",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_3_0;
+        else if (!strcmp("3.1",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_3_1;
+        else if (!strcmp("3.2",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_3_2;
+        else if (!strcmp("4.0",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_4_0;
+        else if (!strcmp("4.1",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_4_1;
+        else if (!strcmp("4.2",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_4_2;
+        else if (!strcmp("5.0",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_5_0;
+        else if (!strcmp("5.1",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_5_1;
+        else if (!strcmp("5.2",  level)) *profile_level_val = kVTProfileLevel_H264_Baseline_5_2;
+        else {
+            av_log(avctx, AV_LOG_ERROR, "Unrecognized level %s\n", vtctx->level);
+            return false;
+        }
+    } else if (!av_strcasecmp("main", profile)) {
+        if      (!strcmp("auto", level)) *profile_level_val = kVTProfileLevel_H264_Main_AutoLevel;
+        else if (!strcmp("3.0",  level)) *profile_level_val = kVTProfileLevel_H264_Main_3_0;
+        else if (!strcmp("3.1",  level)) *profile_level_val = kVTProfileLevel_H264_Main_3_1;
+        else if (!strcmp("3.2",  level)) *profile_level_val = kVTProfileLevel_H264_Main_3_2;
+        else if (!strcmp("4.0",  level)) *profile_level_val = kVTProfileLevel_H264_Main_4_0;
+        else if (!strcmp("4.1",  level)) *profile_level_val = kVTProfileLevel_H264_Main_4_1;
+        else if (!strcmp("4.2",  level)) *profile_level_val = kVTProfileLevel_H264_Main_4_2;
+        else if (!strcmp("5.0",  level)) *profile_level_val = kVTProfileLevel_H264_Main_5_0;
+        else if (!strcmp("5.1",  level)) *profile_level_val = kVTProfileLevel_H264_Main_5_1;
+        else if (!strcmp("5.2",  level)) *profile_level_val = kVTProfileLevel_H264_Main_5_2;
+        else {
+            av_log(avctx, AV_LOG_ERROR, "Unrecognized level %s\n", vtctx->level);
+            return false;
+        }
+    } else if (!av_strcasecmp("high", profile)) {
+        if      (!strcmp("auto", level)) *profile_level_val = kVTProfileLevel_H264_High_AutoLevel;
+        else if (!strcmp("3.0",  level)) *profile_level_val = kVTProfileLevel_H264_High_3_0;
+        else if (!strcmp("3.1",  level)) *profile_level_val = kVTProfileLevel_H264_High_3_1;
+        else if (!strcmp("3.2",  level)) *profile_level_val = kVTProfileLevel_H264_High_3_2;
+        else if (!strcmp("4.0",  level)) *profile_level_val = kVTProfileLevel_H264_High_4_0;
+        else if (!strcmp("4.1",  level)) *profile_level_val = kVTProfileLevel_H264_High_4_1;
+        else if (!strcmp("4.2",  level)) *profile_level_val = kVTProfileLevel_H264_High_4_2;
+        else if (!strcmp("5.0",  level)) *profile_level_val = kVTProfileLevel_H264_High_5_0;
+        else if (!strcmp("5.1",  level)) *profile_level_val = kVTProfileLevel_H264_High_5_1;
+        else if (!strcmp("5.2",  level)) *profile_level_val = kVTProfileLevel_H264_High_5_2;
+        else {
+            av_log(avctx, AV_LOG_ERROR, "Unrecognized level %s\n", vtctx->level);
+            return false;
+        }
+    } else {
+        av_log(avctx, AV_LOG_ERROR, "Unrecognized profile %s\n", vtctx->profile);
+        return false;
+    }
+
+    return true;
+}
+
+static av_cold int vtenc_init(AVCodecContext *avctx)
+{
+    CFMutableDictionaryRef enc_info;
+    CMVideoCodecType       codec_type;
+    VTEncContext           *vtctx = avctx->priv_data;
+    CFStringRef            profile_level;
+    SInt32                 bit_rate = avctx->bit_rate;
+    CFNumberRef            bit_rate_num;
+    int                    status;
+
+    codec_type = get_cm_codec_type(avctx->codec_id);
+    if (!codec_type) {
+        av_log(avctx, AV_LOG_ERROR, "Error: no mapping for AVCodecID %d\n", avctx->codec_id);
+        return AVERROR(EINVAL);
+    }
+
+    vtctx->has_b_frames = avctx->has_b_frames || avctx->max_b_frames > 0;
+
+    if (!get_vt_profile_level(avctx, &profile_level)) return AVERROR(EINVAL);
+
+    vtctx->session = NULL;
+
+    enc_info = CFDictionaryCreateMutable(
+        kCFAllocatorDefault,
+        20,
+        &kCFCopyStringDictionaryKeyCallBacks,
+        &kCFTypeDictionaryValueCallBacks
+    );
+
+    if (!enc_info) return AVERROR(ENOMEM);
+
+#if !TARGET_OS_IPHONE
+    CFDictionarySetValue(enc_info, kVTVideoEncoderSpecification_RequireHardwareAcceleratedVideoEncoder, kCFBooleanTrue);
+    CFDictionarySetValue(enc_info, kVTVideoEncoderSpecification_EnableHardwareAcceleratedVideoEncoder,  kCFBooleanTrue);
+#endif
+
+    status = VTCompressionSessionCreate(
+        kCFAllocatorDefault,
+        avctx->width,
+        avctx->height,
+        codec_type,
+        enc_info,
+        NULL,
+        kCFAllocatorDefault,
+        vtenc_output_callback,
+        avctx,
+        &vtctx->session
+    );
+
+#if !TARGET_OS_IPHONE
+    if (status != 0 || !vtctx->session) {
+        CFDictionaryRemoveValue(enc_info, kVTVideoEncoderSpecification_RequireHardwareAcceleratedVideoEncoder);
+
+        status = VTCompressionSessionCreate(
+            kCFAllocatorDefault,
+            avctx->width,
+            avctx->height,
+            codec_type,
+            enc_info,
+            NULL,
+            kCFAllocatorDefault,
+            vtenc_output_callback,
+            avctx,
+            &vtctx->session
+        );
+    }
+#endif
+
+    CFRelease(enc_info);
+
+    if (status || !vtctx->session) {
+        av_log(avctx, AV_LOG_ERROR, "Error: cannot create compression session: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    bit_rate_num = CFNumberCreate(kCFAllocatorDefault,
+                                  kCFNumberSInt32Type,
+                                  &bit_rate);
+    if (!bit_rate_num) return AVERROR(ENOMEM);
+
+    status = VTSessionSetProperty(vtctx->session,
+                                  kVTCompressionPropertyKey_AverageBitRate,
+                                  bit_rate_num);
+    CFRelease(bit_rate_num);
+
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error setting bitrate property: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    if (profile_level) {
+        status = VTSessionSetProperty(vtctx->session,
+                                      kVTCompressionPropertyKey_ProfileLevel,
+                                      profile_level);
+        if (status) {
+            av_log(avctx, AV_LOG_ERROR, "Error setting profile/level property: %d\n", status);
+            return AVERROR_EXTERNAL;
+        }
+    }
+
+    if (avctx->gop_size > 0) {
+        CFNumberRef interval = CFNumberCreate(kCFAllocatorDefault,
+                                              kCFNumberIntType,
+                                              &avctx->gop_size);
+        status = VTSessionSetProperty(vtctx->session,
+                                      kVTCompressionPropertyKey_MaxKeyFrameInterval,
+                                      interval);
+
+        if (status) {
+            av_log(avctx, AV_LOG_ERROR, "Error setting 'max key-frame interval' property: %d\n", status);
+            return AVERROR_EXTERNAL;
+        }
+    }
+
+    if (!vtctx->has_b_frames) {
+        status = VTSessionSetProperty(vtctx->session,
+                                      kVTCompressionPropertyKey_AllowFrameReordering,
+                                      kCFBooleanFalse);
+
+        if (status) {
+            av_log(avctx, AV_LOG_ERROR, "Error setting 'allow frame reordering' property: %d\n", status);
+            return AVERROR_EXTERNAL;
+        }
+    }
+
+    status = VTCompressionSessionPrepareToEncodeFrames(vtctx->session);
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error: cannot prepare encoder: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    pthread_mutex_init(&vtctx->lock, NULL);
+    pthread_cond_init(&vtctx->cv_sample_sent, NULL);
+    vtctx->dts_delta = vtctx->has_b_frames ? -1 : 0;
+
+    return 0;
+}
+
+static void vtenc_get_frame_info(CMSampleBufferRef buffer, bool *is_key_frame)
+{
+    CFArrayRef      attachments;
+    CFDictionaryRef attachment;
+    CFBooleanRef    not_sync;
+    CFIndex         len;
+
+    attachments = CMSampleBufferGetSampleAttachmentsArray(buffer, false);
+    len = !attachments ? 0 : CFArrayGetCount(attachments);
+
+    if (!len) {
+        *is_key_frame = true;
+        return;
+    }
+
+    attachment = CFArrayGetValueAtIndex(attachments, 0);
+
+    if (CFDictionaryGetValueIfPresent(attachment,
+                                      kCMSampleAttachmentKey_NotSync,
+                                      (const void **)&not_sync))
+    {
+        *is_key_frame = !CFBooleanGetValue(not_sync);
+    } else {
+        *is_key_frame = true;
+    }
+}
+
+/**
+ * Replaces length codes with H.264 Annex B start codes.
+ * length_code_size must equal sizeof(start_code).
+ * On failure, the contents of data may have been modified.
+ *
+ * @param length_code_size Byte length of each length code
+ * @param data Call with NAL units prefixed with length codes.
+ *             On success, the length codes are replace with
+ *             start codes.
+ * @param size Length of data, excluding any padding.
+ * @return 0 on success
+ *         AVERROR_BUFFER_TOO_SMALL if length code size is smaller
+ *         than a start code or if a length_code in data specifies
+ *         data beyond the end of its buffer.
+ */
+static int replace_length_codes(size_t  length_code_size,
+                                uint8_t *data,
+                                size_t  size)
+{
+    size_t remaining_size = size;
+
+    if (length_code_size != sizeof(start_code)) {
+        av_log(NULL, AV_LOG_ERROR, "Start code size and length code size not equal.\n");
+        return AVERROR_BUFFER_TOO_SMALL;
+    }
+
+    while (remaining_size > 0) {
+        size_t box_len = 0;
+        size_t i;
+
+        for (i = 0; i < length_code_size; i++) {
+            box_len <<= 8;
+            box_len |= data[i];
+        }
+
+        if (remaining_size < box_len + sizeof(start_code)) {
+            av_log(NULL, AV_LOG_ERROR, "Length is out of range.\n");
+            AVERROR_BUFFER_TOO_SMALL;
+        }
+
+        memcpy(data, start_code, sizeof(start_code));
+        data += box_len + sizeof(start_code);
+        remaining_size -= box_len + sizeof(start_code);
+    }
+
+    return 0;
+}
+
+/**
+ * Copies NAL units and replaces length codes with
+ * H.264 Annex B start codes. On failure, the contents of
+ * dst_data may have been modified.
+ *
+ * @param length_code_size Byte length of each length code
+ * @param src_data NAL units prefixed with length codes.
+ * @param src_size Length of buffer, excluding any padding.
+ * @param dst_data Must be zeroed before calling this function.
+ *                 Contains the copied NAL units prefixed with
+ *                 start codes when the function returns
+ *                 successfully.
+ * @param dst_size Length of dst_data
+ * @return 0 on success
+ *         AVERROR_INVALIDDATA if length_code_size is invalid
+ *         AVERROR_BUFFER_TOO_SMALL if dst_data is too small
+ *         or if a length_code in src_data specifies data beyond
+ *         the end of its buffer.
+ */
+static int copy_replace_length_codes(
+    size_t        length_code_size,
+    const uint8_t *src_data,
+    size_t        src_size,
+    uint8_t       *dst_data,
+    size_t        dst_size)
+{
+    size_t remaining_src_size = src_size;
+    size_t remaining_dst_size = dst_size;
+
+    if (length_code_size > 4) {
+        return AVERROR_INVALIDDATA;
+    }
+
+    while (remaining_src_size > 0) {
+        size_t curr_src_len;
+        size_t curr_dst_len;
+        size_t box_len = 0;
+        size_t i;
+
+        uint8_t       *dst_box;
+        const uint8_t *src_box;
+
+        for (i = 0; i < length_code_size; i++) {
+            box_len <<= 8;
+            box_len |= src_data[i];
+        }
+
+        curr_src_len = box_len + length_code_size;
+        curr_dst_len = box_len + sizeof(start_code);
+
+        if (remaining_src_size < curr_src_len) {
+            return AVERROR_BUFFER_TOO_SMALL;
+        }
+
+        if (remaining_dst_size < curr_dst_len) {
+            return AVERROR_BUFFER_TOO_SMALL;
+        }
+
+        dst_box = dst_data + sizeof(start_code);
+        src_box = src_data + length_code_size;
+
+        memcpy(dst_data, start_code, sizeof(start_code));
+        memcpy(dst_box,  src_box,    box_len);
+
+        src_data += curr_src_len;
+        dst_data += curr_dst_len;
+
+        remaining_src_size -= curr_src_len;
+        remaining_dst_size -= curr_dst_len;
+    }
+
+    return 0;
+}
+
+static int vtenc_cm_to_avpacket(
+    AVCodecContext    *avctx,
+    CMSampleBufferRef sample_buffer,
+    AVPacket          *pkt)
+{
+    VTEncContext *vtctx = avctx->priv_data;
+
+    int     status;
+    bool    is_key_frame;
+    bool    add_header;
+    char    *buf_data;
+    size_t  length_code_size;
+    size_t  header_size = 0;
+    size_t  in_buf_size;
+    int64_t dts_delta;
+    int64_t time_base_num;
+    CMTime  pts;
+    CMTime  dts;
+
+    CMBlockBufferRef            block;
+    CMVideoFormatDescriptionRef vid_fmt;
+
+
+    vtenc_get_frame_info(sample_buffer, &is_key_frame);
+    status = get_length_code_size(avctx, sample_buffer, &length_code_size);
+    if (status) return status;
+
+    add_header = is_key_frame && !(avctx->flags & AV_CODEC_FLAG_GLOBAL_HEADER);
+
+    if (add_header) {
+        vid_fmt = CMSampleBufferGetFormatDescription(sample_buffer);
+        if (!vid_fmt) {
+            av_log(avctx, AV_LOG_ERROR, "Cannot get format description.\n");
+        }
+
+        int status = get_params_size(avctx, vid_fmt, &header_size);
+        if (status) return status;
+    }
+
+    block = CMSampleBufferGetDataBuffer(sample_buffer);
+    if (!block) {
+        av_log(avctx, AV_LOG_ERROR, "Could not get block buffer from sample buffer.\n");
+        return AVERROR_EXTERNAL;
+    }
+
+
+    status = CMBlockBufferGetDataPointer(block, 0, &in_buf_size, NULL, &buf_data);
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error: cannot get data pointer: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    size_t out_buf_size = header_size + in_buf_size;
+    bool can_reuse_cmbuffer = !add_header &&
+                              !pkt->data  &&
+                              length_code_size == sizeof(start_code);
+
+    av_init_packet(pkt);
+
+    if (can_reuse_cmbuffer) {
+        AVBufferRef* buf_ref = av_buffer_create(
+            buf_data,
+            out_buf_size,
+            vtenc_free_block,
+            block,
+            0
+        );
+
+        if (!buf_ref) return AVERROR(ENOMEM);
+
+        CFRetain(block);
+
+        pkt->buf  = buf_ref;
+        pkt->data = buf_data;
+        pkt->size = in_buf_size;
+
+        status = replace_length_codes(length_code_size, pkt->data, pkt->size);
+        if (status) {
+            av_log(avctx, AV_LOG_ERROR, "Error replacing length codes: %d\n", status);
+            return status;
+        }
+    } else {
+        if (!pkt->data) {
+            status = av_new_packet(pkt, out_buf_size);
+            if(status) return status;
+        }
+
+        if (pkt->size < out_buf_size) {
+            av_log(avctx, AV_LOG_ERROR, "Error: packet's buffer is too small.\n");
+            return AVERROR_BUFFER_TOO_SMALL;
+        }
+
+        if (add_header) {
+            status = copy_param_sets(avctx, vid_fmt, pkt->data, out_buf_size);
+            if(status) return status;
+        }
+
+        status = copy_replace_length_codes(
+            length_code_size,
+            buf_data,
+            in_buf_size,
+            pkt->data + header_size,
+            pkt->size - header_size
+        );
+
+        if (status) {
+            av_log(avctx, AV_LOG_ERROR, "Error copying packet data: %d", status);
+            return status;
+        }
+    }
+
+    if (is_key_frame) {
+        pkt->flags |= AV_PKT_FLAG_KEY;
+    }
+
+    pts = CMSampleBufferGetPresentationTimeStamp(sample_buffer);
+    dts = CMSampleBufferGetDecodeTimeStamp      (sample_buffer);
+
+    dts_delta = vtctx->dts_delta >= 0 ? vtctx->dts_delta : 0;
+    time_base_num = avctx->time_base.num;
+    pkt->pts = pts.value / time_base_num;
+    pkt->dts = dts.value / time_base_num - dts_delta;
+
+    return 0;
+}
+
+/*
+ * contiguous_buf_size is 0 if not contiguous, and the size of the buffer
+ * containing all planes if so.
+ */
+static int get_cv_pixel_info(
+    AVCodecContext *avctx,
+    const AVFrame  *frame,
+    int            *color,
+    int            *plane_count,
+    size_t         *widths,
+    size_t         *heights,
+    size_t         *strides,
+    size_t         *contiguous_buf_size)
+{
+    VTEncContext *vtctx = avctx->priv_data;
+    int av_format       = frame->format;
+    int av_color_range  = frame->color_range;
+    int i;
+
+    switch (av_format) {
+    case AV_PIX_FMT_NV12:
+        switch (av_color_range) {
+        case AVCOL_RANGE_MPEG:
+            *color = kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange;
+            break;
+
+        case AVCOL_RANGE_JPEG:
+            *color = kCVPixelFormatType_420YpCbCr8BiPlanarFullRange;
+            break;
+
+        default:
+            if (!vtctx->warned_color_range) {
+                vtctx->warned_color_range = true;
+                av_log(avctx, AV_LOG_WARNING, "Color range not set for NV12. Using MPEG range.\n");
+            }
+            *color = kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange;
+        }
+
+        *plane_count = 2;
+
+        widths [0] = avctx->width;
+        heights[0] = avctx->height;
+        strides[0] = frame ? frame->linesize[0] : avctx->width;
+
+        widths [1] = (avctx->width  + 1) / 2;
+        heights[1] = (avctx->height + 1) / 2;
+        strides[1] = frame ? frame->linesize[1] : (avctx->width + 1) & -2;
+        break;
+
+    case AV_PIX_FMT_YUV420P:
+        switch (av_color_range) {
+        case AVCOL_RANGE_MPEG:
+            *color = kCVPixelFormatType_420YpCbCr8Planar;
+            break;
+
+        case AVCOL_RANGE_JPEG:
+            *color = kCVPixelFormatType_420YpCbCr8PlanarFullRange;
+            break;
+
+        default:
+            if (!vtctx->warned_color_range) {
+                vtctx->warned_color_range = true;
+                av_log(avctx, AV_LOG_WARNING, "Color range not set for YUV 4:2:0. Using MPEG range.\n");
+            }
+            *color = kCVPixelFormatType_420YpCbCr8Planar;
+        }
+
+        *plane_count = 3;
+
+        widths [0] = avctx->width;
+        heights[0] = avctx->height;
+        strides[0] = frame ? frame->linesize[0] : avctx->width;
+
+        widths [1] = (avctx->width  + 1) / 2;
+        heights[1] = (avctx->height + 1) / 2;
+        strides[1] = frame ? frame->linesize[1] : (avctx->width + 1) / 2;
+
+        widths [2] = (avctx->width  + 1) / 2;
+        heights[2] = (avctx->height + 1) / 2;
+        strides[2] = frame ? frame->linesize[2] : (avctx->width + 1) / 2;
+        break;
+
+    default: return AVERROR(EINVAL);
+    }
+
+    *contiguous_buf_size = 0;
+    for (i = 0; i < *plane_count; i++) {
+        if (i < *plane_count - 1 &&
+            frame->data[i] + strides[i] * heights[i] != frame->data[i + 1]) {
+            *contiguous_buf_size = 0;
+            break;
+        }
+
+        *contiguous_buf_size += strides[i] * heights[i];
+    }
+
+    return 0;
+}
+
+static void free_avframe(
+    void       *CV_NULLABLE release_ctx,
+    const void *CV_NULLABLE data,
+    size_t                  size,
+    size_t                  plane_count,
+    const void *CV_NULLABLE plane_addresses[])
+{
+    AVFrame *frame = release_ctx;
+    av_frame_free(&frame);
+}
+
+static int copy_avframe_to_pixel_buffer(AVCodecContext   *avctx,
+                                        const AVFrame    *frame,
+                                        CVPixelBufferRef cv_img,
+                                        const size_t     *plane_strides,
+                                        const size_t     *plane_rows)
+{
+    int i, j;
+    size_t plane_count;
+    int status;
+    int rows;
+    int src_stride;
+    int dst_stride;
+    uint8_t *src_addr;
+    uint8_t *dst_addr;
+    size_t copy_bytes;
+
+    status = CVPixelBufferLockBaseAddress(cv_img, 0);
+    if (status) {
+        av_log(
+            avctx,
+            AV_LOG_ERROR,
+            "Error: Could not lock base address of CVPixelBuffer: %d.\n",
+            status
+        );
+    }
+
+    if (CVPixelBufferIsPlanar(cv_img)) {
+        plane_count = CVPixelBufferGetPlaneCount(cv_img);
+        for (i = 0; frame->data[i]; i++) {
+            if (i == plane_count) {
+                CVPixelBufferUnlockBaseAddress(cv_img, 0);
+                av_log(avctx,
+                    AV_LOG_ERROR,
+                    "Error: different number of planes in AVFrame and CVPixelBuffer.\n"
+                );
+
+                return AVERROR_EXTERNAL;
+            }
+
+            dst_addr = (uint8_t*)CVPixelBufferGetBaseAddressOfPlane(cv_img, i);
+            src_addr = (uint8_t*)frame->data[i];
+            dst_stride = CVPixelBufferGetBytesPerRowOfPlane(cv_img, i);
+            src_stride = plane_strides[i];
+            rows = plane_rows[i];
+
+            if (dst_stride == src_stride) {
+                size_t dst_rows = CVPixelBufferGetHeightOfPlane(cv_img, i);
+
+                memcpy(dst_addr, src_addr, src_stride * rows);
+            } else {
+                copy_bytes = dst_stride < src_stride ? dst_stride : src_stride;
+
+                for (j = 0; j < rows; j++) {
+                    memcpy(dst_addr + j * dst_stride, src_addr + j * src_stride, copy_bytes);
+                }
+            }
+        }
+    } else {
+        if (frame->data[1]) {
+            CVPixelBufferUnlockBaseAddress(cv_img, 0);
+            av_log(avctx,
+                AV_LOG_ERROR,
+                "Error: different number of planes in AVFrame and non-planar CVPixelBuffer.\n"
+            );
+
+            return AVERROR_EXTERNAL;
+        }
+
+        dst_addr = (uint8_t*)CVPixelBufferGetBaseAddress(cv_img);
+        src_addr = (uint8_t*)frame->data[0];
+        dst_stride = CVPixelBufferGetBytesPerRow(cv_img);
+        src_stride = plane_strides[0];
+        rows = plane_rows[0];
+
+        if (dst_stride == src_stride) {
+            memcpy(dst_addr, src_addr, src_stride * rows);
+        } else {
+            copy_bytes = dst_stride < src_stride ? dst_stride : src_stride;
+
+            for (j = 0; j < rows; j++) {
+                memcpy(dst_addr + j * dst_stride, src_addr + j * src_stride, copy_bytes);
+            }
+        }
+    }
+
+    status = CVPixelBufferUnlockBaseAddress(cv_img, 0);
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error: Could not unlock CVPixelBuffer base address: %d.\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    return 0;
+}
+
+static int create_cv_pixel_buffer(AVCodecContext   *avctx,
+                                  const AVFrame    *frame,
+                                  CVPixelBufferRef *cv_img)
+{
+    int plane_count;
+    int color;
+    size_t widths [AV_NUM_DATA_POINTERS];
+    size_t heights[AV_NUM_DATA_POINTERS];
+    size_t strides[AV_NUM_DATA_POINTERS];
+    int status;
+    size_t contiguous_buf_size;
+
+    memset(widths,  0, sizeof(widths));
+    memset(heights, 0, sizeof(heights));
+    memset(strides, 0, sizeof(strides));
+
+    status = get_cv_pixel_info(
+        avctx,
+        frame,
+        &color,
+        &plane_count,
+        widths,
+        heights,
+        strides,
+        &contiguous_buf_size
+    );
+
+    if (status) {
+        av_log(
+            avctx,
+            AV_LOG_ERROR,
+            "Error: Cannot convert format %d color_range %d: %d\n",
+            frame->format,
+            frame->color_range,
+            status
+        );
+
+        return AVERROR_EXTERNAL;
+    }
+
+#if TARGET_OS_IPHONE
+    status = CVPixelBufferCreate(
+        kCFAllocatorDefault,
+        frame->width,
+        frame->height,
+        color,
+        NULL,
+        cv_img
+    );
+
+    if (status) {
+        return AVERROR_EXTERNAL;
+    }
+
+    status = copy_avframe_to_pixel_buffer(avctx, frame, *cv_img, strides, heights);
+    if (status) {
+        CFRelease(*cv_img);
+        *cv_img = NULL;
+        return status;
+    }
+#else
+    AVFrame *enc_frame = av_frame_alloc();
+    if (!enc_frame) return AVERROR(ENOMEM);
+
+    status = av_frame_ref(enc_frame, frame);
+    if (status) {
+        av_frame_free(&enc_frame);
+        return status;
+    }
+
+    status = CVPixelBufferCreateWithPlanarBytes(
+        kCFAllocatorDefault,
+        enc_frame->width,
+        enc_frame->height,
+        color,
+        NULL,
+        contiguous_buf_size,
+        plane_count,
+        (void **)enc_frame->data,
+        widths,
+        heights,
+        strides,
+        free_avframe,
+        enc_frame,
+        NULL,
+        cv_img
+    );
+
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error: Could not create CVPixelBuffer: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+#endif
+
+    return 0;
+}
+
+static int vtenc_send_frame(AVCodecContext *avctx,
+                            VTEncContext   *vtctx,
+                            const AVFrame  *frame)
+{
+    CMTime time;
+    CVPixelBufferRef cv_img = NULL;
+    int status = create_cv_pixel_buffer(avctx, frame, &cv_img);
+
+    if (status) return status;
+
+    time = CMTimeMake(frame->pts * avctx->time_base.num, avctx->time_base.den);
+    status = VTCompressionSessionEncodeFrame(
+        vtctx->session,
+        cv_img,
+        time,
+        kCMTimeInvalid,
+        NULL,
+        NULL,
+        NULL
+    );
+
+    CFRelease(cv_img);
+
+    if (status) {
+        av_log(avctx, AV_LOG_ERROR, "Error: cannot encode frame: %d\n", status);
+        return AVERROR_EXTERNAL;
+    }
+
+    return 0;
+}
+
+static av_cold int vtenc_frame(
+    AVCodecContext *avctx,
+    AVPacket       *pkt,
+    const AVFrame  *frame,
+    int            *got_packet)
+{
+    VTEncContext *vtctx = avctx->priv_data;
+    bool get_frame;
+    int status;
+    CMSampleBufferRef buf = NULL;
+
+    if (frame) {
+        status = vtenc_send_frame(avctx, vtctx, frame);
+
+        if (status) {
+            status = AVERROR_EXTERNAL;
+            goto end_nopkt;
+        }
+
+        if (vtctx->frame_ct_in == 0) {
+            vtctx->first_pts = frame->pts;
+        } else if(vtctx->frame_ct_in == 1 && vtctx->has_b_frames) {
+            vtctx->dts_delta = frame->pts - vtctx->first_pts;
+        }
+
+        vtctx->frame_ct_in++;
+    } else if(!vtctx->flushing) {
+        vtctx->flushing = true;
+
+        status = VTCompressionSessionCompleteFrames(vtctx->session,
+                                                    kCMTimeIndefinite);
+
+        if (status) {
+            av_log(avctx, AV_LOG_ERROR, "Error flushing frames: %d\n", status);
+            status = AVERROR_EXTERNAL;
+            goto end_nopkt;
+        }
+    }
+
+    *got_packet = 0;
+    get_frame = vtctx->dts_delta >= 0 || !frame;
+    if (!get_frame) {
+        status = 0;
+        goto end_nopkt;
+    }
+
+    status = vtenc_q_pop(vtctx, !frame, &buf);
+    if (status) goto end_nopkt;
+    if (!buf)   goto end_nopkt;
+
+    status = vtenc_cm_to_avpacket(avctx, buf, pkt);
+    CFRelease(buf);
+    if (status) goto end_nopkt;
+
+    *got_packet = 1;
+    return 0;
+
+end_nopkt:
+    av_packet_unref(pkt);
+    return status;
+}
+
+static av_cold int vtenc_close(AVCodecContext *avctx)
+{
+    VTEncContext *vtctx = avctx->priv_data;
+
+    if(!vtctx->session) return 0;
+
+    VTCompressionSessionInvalidate(vtctx->session);
+    pthread_cond_destroy(&vtctx->cv_sample_sent);
+    pthread_mutex_destroy(&vtctx->lock);
+    CFRelease(vtctx->session);
+    vtctx->session = NULL;
+
+    return 0;
+}
+
+static const enum AVPixelFormat pix_fmts[] = {
+    AV_PIX_FMT_NV12,
+#if !TARGET_OS_IPHONE
+    AV_PIX_FMT_YUV420P,
+#endif
+    AV_PIX_FMT_NONE
+};
+
+#define OFFSET(x) offsetof(VTEncContext, x)
+#define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
+static const AVOption options[] = {
+    { "profile", "Profile", OFFSET(profile), AV_OPT_TYPE_STRING, { 0 },         0, 0, VE },
+    { "level",   "Level",   OFFSET(level),   AV_OPT_TYPE_STRING, { .str=NULL }, 0, 0, VE },
+    { NULL },
+};
+
+static const AVClass vtenc_class = {
+    .class_name = "vtenc",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVCodec ff_vtenc_encoder = {
+    .name             = "vtenc",
+    .long_name        = NULL_IF_CONFIG_SMALL("VideoToolbox H.264 Encoder"),
+    .type             = AVMEDIA_TYPE_VIDEO,
+    .id               = AV_CODEC_ID_H264,
+    .priv_data_size   = sizeof(VTEncContext),
+    .pix_fmts         = pix_fmts,
+    .init             = vtenc_init,
+    .encode2          = vtenc_frame,
+    .close            = vtenc_close,
+    .capabilities     = AV_CODEC_CAP_DELAY,
+    .priv_class       = &vtenc_class,
+    .caps_internal    = FF_CODEC_CAP_INIT_THREADSAFE |
+                        FF_CODEC_CAP_INIT_CLEANUP,
+};
-- 
2.5.4 (Apple Git-61)



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