[FFmpeg-devel] [PATCH 2/2] hwaccel: add VideoToolbox support.
Michael Niedermayer
michaelni at gmx.at
Tue Sep 18 05:04:20 CEST 2012
On Sun, Sep 16, 2012 at 08:38:05PM +0200, Sebastien Zwickert wrote:
> ---
> Changelog | 1 +
> MAINTAINERS | 1 +
> configure | 12 ++
> libavcodec/Makefile | 7 +
> libavcodec/allcodecs.c | 4 +
> libavcodec/h264.c | 1 +
> libavcodec/mpeg12.c | 3 +
> libavcodec/mpegvideo.c | 1 +
> libavcodec/vt.c | 365 ++++++++++++++++++++++++++++++++++++++++++++++
> libavcodec/vt.h | 186 +++++++++++++++++++++++
> libavcodec/vt_h264.c | 79 ++++++++++
> libavcodec/vt_internal.h | 42 ++++++
> libavcodec/vt_mpeg2.c | 62 ++++++++
> libavcodec/vt_mpeg4.c | 77 ++++++++++
> libavutil/pixdesc.c | 6 +
> libavutil/pixfmt.h | 1 +
> 16 files changed, 848 insertions(+)
> create mode 100644 libavcodec/vt.c
> create mode 100644 libavcodec/vt.h
> create mode 100644 libavcodec/vt_h264.c
> create mode 100644 libavcodec/vt_internal.h
> create mode 100644 libavcodec/vt_mpeg2.c
> create mode 100644 libavcodec/vt_mpeg4.c
[...]
> diff --git a/libavcodec/vt.c b/libavcodec/vt.c
> new file mode 100644
> index 0000000..e357b56
> --- /dev/null
> +++ b/libavcodec/vt.c
> @@ -0,0 +1,365 @@
> +/*
> + * VideoToolbox hardware acceleration
> + *
> + * copyright (c) 2012 Sebastien Zwickert
> + *
> + * 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 "libavutil/avutil.h"
> +#include "libavformat/avio.h"
> +#include "libavformat/movenc.h"
> +
> +#include "vt_internal.h"
> +
> +static CFDataRef vt_esds_extradata_create(AVCodecContext *avctx)
> +{
> + CFDataRef data = NULL;
> + MOVTrack *track = NULL;
> + AVIOContext *pb = NULL;
> + uint8_t *buf = NULL;
> + int sb = 8; // skip first atom info : size and fourcc
> + int buf_size = 3 + 5 + 13 + 5 + avctx->extradata_size + 3;
> + // ES_DescrTag data + DecoderConfigDescrTag + data + DecSpecificInfoTag + size + SLConfigDescriptor
> + int padding = 12 + sb;
> + int s;
> +
> + if (!(buf = av_mallocz(buf_size + padding)))
> + goto end;
> +
> + if (!(track = av_mallocz(sizeof(MOVTrack))))
> + goto end;
> +
> + pb = avio_alloc_context(buf, buf_size + padding, 1, NULL, NULL, NULL, NULL);
the use of libavformat from libavcodec is problematic as it would make
libavcodec depend on libavformat if VideoToolbox support is enabled.
I think many people would be opposed to such dependancy.
the solution here is either to undo the factorization or to change
the code to use only functions available in libavcodec/libavutil
and then change the libavformat part to be based on top of this.
[...]
> +static void vt_decoder_callback(void *vt_hw_ctx,
> + void *sourceFrameRefCon,
> + OSStatus status,
> + VTDecodeInfoFlags flags,
> + CVImageBufferRef image_buffer,
> + CMTime pts,
> + CMTime duration)
> +{
> + struct vt_context *vt_ctx = vt_hw_ctx;
> + vt_ctx->cv_buffer = NULL;
> +
> + if (!image_buffer)
> + return;
> +
> + if (vt_ctx->cv_pix_fmt != CVPixelBufferGetPixelFormatType(image_buffer))
> + return;
Are these return cases normal occurances or are these error/warning
conditions ? if later it might make sense to at least produce a
av_log(X, AV_LOG_DEBUG,...) in the case
> +
> + vt_ctx->cv_buffer = CVPixelBufferRetain(image_buffer);
> +}
> +
> +static int vt_session_decode_frame(struct vt_context *vt_ctx)
> +{
> + OSStatus status;
> + CMSampleBufferRef sample_buf;
> +
> + sample_buf = vt_sample_buffer_create(vt_ctx->cm_fmt_desc,
> + vt_ctx->priv_bitstream,
> + vt_ctx->priv_bitstream_size);
> +
> + if (!sample_buf)
> + return -1;
> +
> + status = VTDecompressionSessionDecodeFrame(vt_ctx->session,
> + sample_buf,
> + 0, // decodeFlags
> + NULL, // sourceFrameRefCon
> + 0); // infoFlagsOut
> + if (status == noErr)
> + status = VTDecompressionSessionWaitForAsynchronousFrames(vt_ctx->session);
> +
> + CFRelease(sample_buf);
> +
> + return status;
> +}
is a OSStatus guranteed to fit in a int ? it is implicitly cast to
one here.
also the error code is propagated down to hwaccel end_frame, later
needs negative values for errors, are errors in OSStatus guranteed
to be negative ? (i tried to find some docs but failed)
[...]
> +/**
> + * This structure is used to provide the necessary configuration and data
> + * to the VideoToolbox FFmpeg HWAccel implementation.
> + *
> + * The application must make it available as AVCodecContext.hwaccel_context.
> + */
> +struct vt_context {
> + /**
> + * VideoToolbox decompression session.
> + *
> + * - encoding: unused.
> + * - decoding: Set/Unset by libavcodec.
> + */
> + VTDecompressionSessionRef session;
> +
> + /**
> + * The width of encoded video.
> + *
> + * - encoding: unused.
> + * - decoding: Set/Unset by user.
> + */
> + int width;
> +
> + /**
> + * The height of encoded video.
> + *
> + * - encoding: unused.
> + * - decoding: Set/Unset by user.
> + */
> + int height;
> +
these 2 seem unused
[...]
> +static int vt_mpeg2_end_frame(AVCodecContext *avctx)
> +{
> + return ff_vt_end_frame(avctx);
> +}
> +
> +AVHWAccel ff_mpeg2_vt_hwaccel = {
> + .name = "mpeg2_vt",
> + .type = AVMEDIA_TYPE_VIDEO,
> + .id = AV_CODEC_ID_MPEG2VIDEO,
> + .pix_fmt = PIX_FMT_VT_VLD,
> + .start_frame = vt_mpeg2_start_frame,
> + .end_frame = vt_mpeg2_end_frame,
> + .decode_slice = vt_mpeg2_decode_slice,
> +};
the vt_mpeg2_end_frame wraper function seems unneeded ff_vt_end_frame
could directly be used in the struct
the same applies to vt_h264_end_frame() and vt_mpeg4_end_frame()
[...]
> +static int vt_mpeg4_start_frame(AVCodecContext *avctx,
> + const uint8_t *buffer,
> + uint32_t size)
> +{
> + struct vt_context *vt_ctx = avctx->hwaccel_context;
> +
> + if (!vt_ctx->session)
> + return -1;
> +
> + return ff_vt_buffer_copy(vt_ctx, buffer, size);
> +}
> +
> +static int vt_mpeg4_decode_slice(AVCodecContext *avctx,
> + const uint8_t *buffer,
> + uint32_t size)
> +{
> + struct vt_context *vt_ctx = avctx->hwaccel_context;
> +
> + if (!vt_ctx->session)
> + return -1;
> +
> + return 0;
> +}
these 2 look redundant relative to the mpeg2 variants
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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