[FFmpeg-devel] [PATCH] lavc: add lavfi metadata support. [NEW ATTEMPT]

Clément Bœsch ubitux at gmail.com
Wed Oct 17 00:11:08 CEST 2012


This commit introduces a new AVPacket side data type:
AV_PKT_DATA_METADATA. Its main goal is to provide a way to transmit the
metadata from the AVFilterBufferRef up to the AVFrame. This is at the
moment "only" useful for lavfi input from libavdevice: lavd/lavfi only
outputs packets, and the metadata from the buffer ref kept in its
context needs to be transmitted from the packet to the frame by the
decoders. The buffer ref can be destroyed at any time (along with the
metadata), and a duplication of the AVPacket needs to duplicate the
metadata as well, so the choice of using the side data to store them was
selected.

Making sure lavd/lavfi raises the metadata is useful to allow tools like
ffprobe to access the filters metadata (it is at the moment the only
way); ffprobe will now automatically show the AVFrame metadata in any
customizal output format for users. API users will also be able to
access the AVFrame->metadata pointer the same way ffprobe does
(av_frame_get_metadata).

All the changes are done in this single commit to avoid some memory
leaks: for instances, the changes in lavfi/avcodec.c are meant to
duplicate the metadata from the buffer ref into the AVFrame. Unless we
have an internal way of freeing the AVFrame->metadata automatically, it
will leak in most of the user apps. To fix this problem, we link
avctx->metadata to the current frame->metadata and free it at each
decode frame call (and in the codec closing callback for the last one).
But doing this also means to update the way the tiff decoder already
handles the AVFrame->metadata (it's the only one decoder handling
metadata at the moment), by making sure it is not trying to free a
pointer already freed by the lavc internals.

The lavfi/avcodec.c buffer ref code is based on an old Thomas Kühnel
work, the rest of the code belongs to the commit author.

Signed-off-by: Thomas Kühnel <kuehnelth at googlemail.com>
Signed-off-by: Clément Bœsch <ubitux at gmail.com>

TODO: lavc and lavfi minor bump
TODO: update APIChanges
---
Note: when this commit is approved, the two others (silencedetect and scene
detection in vf select) will be pushed at the same time.
---
 libavcodec/avcodec.h   | 13 +++++++++++++
 libavcodec/tiff.c      |  7 +++----
 libavcodec/utils.c     | 29 +++++++++++++++++++++++++++++
 libavdevice/lavfi.c    | 22 ++++++++++++++++++++++
 libavfilter/avcodec.c  |  3 +++
 libavfilter/avfilter.h |  2 ++
 libavfilter/buffer.c   |  8 ++++++++
 7 files changed, 80 insertions(+), 4 deletions(-)

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 0b3a19a..06bdbde 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -942,6 +942,12 @@ enum AVPacketSideDataType {
      * @endcode
      */
     AV_PKT_DATA_JP_DUALMONO,
+
+    /**
+     * A list of zero terminated key/value strings. There is no end marker for
+     * the list, so it is required to rely on the side data size to stop.
+     */
+    AV_PKT_DATA_METADATA,
 };
 
 typedef struct AVPacket {
@@ -3091,6 +3097,13 @@ typedef struct AVCodecContext {
     int64_t pts_correction_num_faulty_dts; /// Number of incorrect DTS values so far
     int64_t pts_correction_last_pts;       /// PTS of the last frame
     int64_t pts_correction_last_dts;       /// DTS of the last frame
+
+    /**
+     * Current frame metadata.
+     * - decoding: maintained and used by libavcodec, not intended to be used by user apps
+     * - encoding: unused
+     */
+    AVDictionary *metadata;
 } AVCodecContext;
 
 AVRational av_codec_get_pkt_timebase         (const AVCodecContext *avctx);
diff --git a/libavcodec/tiff.c b/libavcodec/tiff.c
index ad0b0ba..ed86485 100644
--- a/libavcodec/tiff.c
+++ b/libavcodec/tiff.c
@@ -1017,8 +1017,9 @@ static int decode_frame(AVCodecContext *avctx,
     s->compr = TIFF_RAW;
     s->fill_order = 0;
     free_geotags(s);
-    /* free existing metadata */
-    av_dict_free(&s->picture.metadata);
+    /* metadata has been destroyed from lavc internals, that pointer is not
+     * valid anymore */
+    s->picture.metadata = NULL;
 
     // As TIFF 6.0 specification puts it "An arbitrary but carefully chosen number
     // that further identifies the file as a TIFF file"
@@ -1168,8 +1169,6 @@ static av_cold int tiff_end(AVCodecContext *avctx)
     TiffContext *const s = avctx->priv_data;
 
     free_geotags(s);
-    if (avctx->coded_frame && avctx->coded_frame->metadata)
-        av_dict_free(&avctx->coded_frame->metadata);
 
     ff_lzw_decode_close(&s->lzw);
     if (s->picture.data[0])
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index d64de0e..1a5c1c2 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -1551,6 +1551,29 @@ static void apply_param_change(AVCodecContext *avctx, AVPacket *avpkt)
     }
 }
 
+static int set_metadata_from_side_data(AVCodecContext *avctx, AVFrame *frame)
+{
+    int size;
+    const uint8_t *side_meta;
+    const uint8_t *end;
+
+    frame->metadata = NULL;
+    av_dict_free(&avctx->metadata);
+    side_meta = av_packet_get_side_data(avctx->pkt, AV_PKT_DATA_METADATA, &size);
+    if (!side_meta)
+        return 0;
+    end = side_meta + size;
+    while (side_meta < end) {
+        const uint8_t *key = side_meta;
+        const uint8_t *val = side_meta + strlen(key) + 1;
+        int ret = av_dict_set(&frame->metadata, key, val, 0);
+        if (ret < 0)
+            return ret;
+        side_meta = val + strlen(val) + 1;
+    }
+    return 0;
+}
+
 int attribute_align_arg avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture,
                                               int *got_picture_ptr,
                                               const AVPacket *avpkt)
@@ -1572,6 +1595,7 @@ int attribute_align_arg avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi
         int did_split = av_packet_split_side_data(&tmp);
         apply_param_change(avctx, &tmp);
         avctx->pkt = &tmp;
+        set_metadata_from_side_data(avctx, picture);
         if (HAVE_THREADS && avctx->active_thread_type & FF_THREAD_FRAME)
             ret = ff_thread_decode_frame(avctx, picture, got_picture_ptr,
                                          &tmp);
@@ -1588,7 +1612,9 @@ int attribute_align_arg avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi
             if (!picture->width)                   picture->width               = avctx->width;
             if (!picture->height)                  picture->height              = avctx->height;
             if (picture->format == AV_PIX_FMT_NONE)   picture->format              = avctx->pix_fmt;
+
         }
+        avctx->metadata = picture->metadata;
 
         emms_c(); //needed to avoid an emms_c() call before every return;
 
@@ -1692,7 +1718,9 @@ int attribute_align_arg avcodec_decode_audio4(AVCodecContext *avctx,
         apply_param_change(avctx, &tmp);
 
         avctx->pkt = &tmp;
+        set_metadata_from_side_data(avctx, frame);
         ret = avctx->codec->decode(avctx, frame, got_frame_ptr, &tmp);
+        avctx->metadata = frame->metadata;
         if (ret >= 0 && *got_frame_ptr) {
             avctx->frame_number++;
             frame->pkt_dts = avpkt->dts;
@@ -1839,6 +1867,7 @@ av_cold int avcodec_close(AVCodecContext *avctx)
         avctx->internal->byte_buffer_size = 0;
         av_freep(&avctx->internal->byte_buffer);
         av_freep(&avctx->internal);
+        av_dict_free(&avctx->metadata);
     }
 
     if (avctx->priv_data && avctx->codec && avctx->codec->priv_class)
diff --git a/libavdevice/lavfi.c b/libavdevice/lavfi.c
index 944794f..e476262 100644
--- a/libavdevice/lavfi.c
+++ b/libavdevice/lavfi.c
@@ -27,6 +27,7 @@
 
 #include "float.h"              /* DBL_MIN, DBL_MAX */
 
+#include "libavutil/bprint.h"
 #include "libavutil/log.h"
 #include "libavutil/mem.h"
 #include "libavutil/opt.h"
@@ -339,6 +340,27 @@ static int lavfi_read_packet(AVFormatContext *avctx, AVPacket *pkt)
         memcpy(pkt->data, ref->data[0], size);
     }
 
+    if (ref->metadata) {
+        uint8_t *meta;
+        AVDictionaryEntry *e = NULL;
+        AVBPrint meta_buf;
+
+        av_bprint_init(&meta_buf, 0, AV_BPRINT_SIZE_UNLIMITED);
+        while ((e = av_dict_get(ref->metadata, "", e, AV_DICT_IGNORE_SUFFIX))) {
+            av_bprintf(&meta_buf, "%s", e->key);
+            av_bprint_chars(&meta_buf, '\0', 1);
+            av_bprintf(&meta_buf, "%s", e->value);
+            av_bprint_chars(&meta_buf, '\0', 1);
+        }
+        if (!av_bprint_is_complete(&meta_buf) ||
+            !(meta = av_packet_new_side_data(pkt, AV_PKT_DATA_METADATA, meta_buf.len))) {
+            av_bprint_finalize(&meta_buf, NULL);
+            return AVERROR(ENOMEM);
+        }
+        memcpy(meta, meta_buf.str, meta_buf.len);
+        av_bprint_finalize(&meta_buf, NULL);
+    }
+
     pkt->stream_index = stream_idx;
     pkt->pts = ref->pts;
     pkt->pos = ref->pos;
diff --git a/libavfilter/avcodec.c b/libavfilter/avcodec.c
index 313080d..5b5938c 100644
--- a/libavfilter/avcodec.c
+++ b/libavfilter/avcodec.c
@@ -33,6 +33,9 @@ int avfilter_copy_frame_props(AVFilterBufferRef *dst, const AVFrame *src)
     dst->pos    = av_frame_get_pkt_pos(src);
     dst->format = src->format;
 
+    av_dict_free(&dst->metadata);
+    av_dict_copy(&dst->metadata, src->metadata, 0);
+
     switch (dst->type) {
     case AVMEDIA_TYPE_VIDEO:
         dst->video->w                   = src->width;
diff --git a/libavfilter/avfilter.h b/libavfilter/avfilter.h
index 510f28a..dccd420 100644
--- a/libavfilter/avfilter.h
+++ b/libavfilter/avfilter.h
@@ -180,6 +180,8 @@ typedef struct AVFilterBufferRef {
     int perms;                  ///< permissions, see the AV_PERM_* flags
 
     enum AVMediaType type;      ///< media type of buffer data
+
+    AVDictionary *metadata;     ///< dictionary containing metadata key=value tags
 } AVFilterBufferRef;
 
 /**
diff --git a/libavfilter/buffer.c b/libavfilter/buffer.c
index fc65b82..ae1867f 100644
--- a/libavfilter/buffer.c
+++ b/libavfilter/buffer.c
@@ -54,6 +54,10 @@ AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask)
     if (!ret)
         return NULL;
     *ret = *ref;
+
+    ret->metadata = NULL;
+    av_dict_copy(&ret->metadata, ref->metadata, 0);
+
     if (ref->type == AVMEDIA_TYPE_VIDEO) {
         ret->video = av_malloc(sizeof(AVFilterBufferRefVideoProps));
         if (!ret->video) {
@@ -172,6 +176,7 @@ void avfilter_unref_buffer(AVFilterBufferRef *ref)
         av_freep(&ref->video->qp_table);
     av_freep(&ref->video);
     av_freep(&ref->audio);
+    av_dict_free(&ref->metadata);
     av_free(ref);
 }
 
@@ -197,6 +202,9 @@ void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, AVFilterBufferRef *s
     case AVMEDIA_TYPE_AUDIO: *dst->audio = *src->audio; break;
     default: break;
     }
+
+    av_dict_free(&dst->metadata);
+    av_dict_copy(&dst->metadata, src->metadata, 0);
 }
 
 AVFilterBufferRef *ff_copy_buffer_ref(AVFilterLink *outlink,
-- 
1.7.12.2



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