[FFmpeg-devel] [PATCH v4] lavc/audiotoolboxenc: fix noise in encoded audio

[Bang He]

maybe you should  return 1, not return ret

On Wed, Jan 3, 2018 at 12:54 PM, <zhangjiejun1992 at gmail.com> wrote:

> From: Jiejun Zhang <zhangjiejun1992 at gmail.com>
>
> This fixes #6940
>
> Although undocumented, AudioToolbox seems to require the data supplied
> by the callback (i.e. ffat_encode_callback) being unchanged until the
> next time the callback is called. In the old implementation, the
> AVBuffer backing the frame is recycled after the frame is freed, and
> somebody else (maybe the decoder) will write into the AVBuffer and
> change the data. AudioToolbox then encodes some wrong data and noise
> is produced. Retaining a frame reference solves this problem.
> ---
>  libavcodec/audiotoolboxenc.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/libavcodec/audiotoolboxenc.c b/libavcodec/audiotoolboxenc.c
> index 71885d1530..4d8130af96 100644
> --- a/libavcodec/audiotoolboxenc.c
> +++ b/libavcodec/audiotoolboxenc.c
> @@ -48,6 +48,8 @@ typedef struct ATDecodeContext {
>      AudioFrameQueue afq;
>      int eof;
>      int frame_size;
> +
> +    AVFrame* encoding_frame;
>  } ATDecodeContext;
>
>  static UInt32 ffat_get_format_id(enum AVCodecID codec, int profile)
> @@ -442,6 +444,10 @@ static av_cold int ffat_init_encoder(AVCodecContext
> *avctx)
>
>      ff_af_queue_init(avctx, &at->afq);
>
> +    at->encoding_frame = av_frame_alloc();
> +    if (!at->encoding_frame)
> +        return AVERROR(ENOMEM);
> +
>      return 0;
>  }
>
> @@ -453,6 +459,7 @@ static OSStatus ffat_encode_callback(AudioConverterRef
> converter, UInt32 *nb_pac
>      AVCodecContext *avctx = inctx;
>      ATDecodeContext *at = avctx->priv_data;
>      AVFrame *frame;
> +    int ret;
>
>      if (!at->frame_queue.available) {
>          if (at->eof) {
> @@ -475,6 +482,12 @@ static OSStatus ffat_encode_callback(AudioConverterRef
> converter, UInt32 *nb_pac
>      if (*nb_packets > frame->nb_samples)
>          *nb_packets = frame->nb_samples;
>
> +    av_frame_unref(at->encoding_frame);
> +    if ((ret = av_frame_ref(at->encoding_frame, frame)) < 0) {
> +        *nb_packets = 0;
> +        return ret;
> +    }
> +
>      ff_bufqueue_add(avctx, &at->used_frame_queue, frame);
>
>      return 0;
> @@ -565,6 +578,7 @@ static av_cold int ffat_close_encoder(AVCodecContext
> *avctx)
>      ff_bufqueue_discard_all(&at->frame_queue);
>      ff_bufqueue_discard_all(&at->used_frame_queue);
>      ff_af_queue_close(&at->afq);
> +    av_frame_free(&at->encoding_frame);
>      return 0;
>  }
>
> --
> 2.14.3 (Apple Git-98)
>
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