On Wed, 14 Jan 2015 17:23:08 +0100
Michael Niedermayer <michae...@gmx.at> wrote:
> This can be extended easily to skip the buffer growing for codecs which do
> not need it.
>
> Signed-off-by: Michael Niedermayer <michae...@gmx.at>
> ---
> libavcodec/avcodec.h | 8 +++++++-
> libavcodec/utils.c | 12 ++++++++++--
> 2 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 99467bb..ec95194 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -4128,9 +4128,15 @@ int avcodec_decode_audio4(AVCodecContext *avctx,
> AVFrame *frame,
> * Some decoders may support multiple frames in a single AVPacket, such
> * decoders would then just decode the first frame.
> *
> - * @warning The input buffer must be FF_INPUT_BUFFER_PADDING_SIZE larger than
> + * @warning If you use non AVBuffer based AVPackets, then the input buffer
> must
> + * be FF_INPUT_BUFFER_PADDING_SIZE larger than
> * the actual read bytes because some optimized bitstream readers read 32 or
> 64
> * bits at once and could read over the end.
> + * If you do use AVBuffer based AVPackets and the allocated space as
> indicated
> + * by the AVBuffer does not include FF_INPUT_BUFFER_PADDING_SIZE padding then
> + * many decoders will reallocate the buffer.
> + * Most AVPacket as created by the FFmpeg APIs will already include the
> needed
> + * padding.
> *
> * @warning The end of the input buffer buf should be set to 0 to ensure that
> * no overreading happens for damaged MPEG streams.
> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
> index 1ec5cae..eaa0431 100644
> --- a/libavcodec/utils.c
> +++ b/libavcodec/utils.c
> @@ -2332,7 +2332,8 @@ int attribute_align_arg
> avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi
> AVCodecInternal *avci = avctx->internal;
> int ret;
> // copy to ensure we do not change avpkt
> - AVPacket tmp = *avpkt;
> + AVPacket tmp;
> + int did_split = 0;
>
> if (!avctx->codec)
> return AVERROR(EINVAL);
> @@ -2347,8 +2348,15 @@ int attribute_align_arg
> avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi
>
> av_frame_unref(picture);
>
> + if (avpkt->buf && avpkt->size && avpkt->buf->size - avpkt->size <
> FF_INPUT_BUFFER_PADDING_SIZE) {
> + if ((ret = av_grow_packet(avpkt, FF_INPUT_BUFFER_PADDING_SIZE)) < 0)
> + goto fail;
> + tmp.size -= FF_INPUT_BUFFER_PADDING_SIZE;
> + }
> + tmp = *avpkt;
> +
This assumes that AVBuffer is actually always padded. Is this the case?
The user can create custom AVBuffers, with custom allocation and custom
free function.
> if ((avctx->codec->capabilities & CODEC_CAP_DELAY) || avpkt->size ||
> (avctx->active_thread_type & FF_THREAD_FRAME)) {
> - int did_split = av_packet_split_side_data(&tmp);
> + did_split = av_packet_split_side_data(&tmp);
> ret = apply_param_change(avctx, &tmp);
> if (ret < 0) {
> av_log(avctx, AV_LOG_ERROR, "Error applying parameter
> changes.\n");
What's the point of the did_split change?
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