On Thu, 16 Feb 2017 10:29:38 -0800 Aman Gupta <ffm...@tmm1.net> wrote:
> From: Aman Gupta <a...@tmm1.net> > > On some platforms (observed on macOS Sierra with 12" macbook), the VT > decoder will start returning errors when encountering an SPS change in > the h264 bitstream. With this patch, the kVTVideoDecoderBadDataErr > response from the decoder is caught and the decompression session is > recreated with a new avcC. The "bad data" is then fed into the new > decompression session so that it can be decoded correctly. > > I discovered the underlying issue here by running ffmpeg with lldb, > which causes macOS to display debug information from the VT hardware > decoder on stderr. The following errors were shown, which indicated the > need to restart the decoder session with a new SPS/avcC: > > ffmpeg[15127:4094995] GVA error: SPS mismatch ... > ffmpeg[15127:4094995] GVA error: AVF_PushMetaData, first field > kAVF_QT0_SPSPPSBoundaryMarker > ffmpeg[15127:4094995] GVA error: pushMetaData, submitNewJobs > ffmpeg[15127:4094995] GVA warning: OutputQueueReadyCallback status = 1, > buffer == 0x0 > > Tested with the following sample, which contains an SPS change midstream: > http://tmm1.s3.amazonaws.com/videotoolbox/spschange.ts > --- > libavcodec/videotoolbox.c | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) > > diff --git a/libavcodec/videotoolbox.c b/libavcodec/videotoolbox.c > index 9be7bee..159d98d 100644 > --- a/libavcodec/videotoolbox.c > +++ b/libavcodec/videotoolbox.c > @@ -38,6 +38,9 @@ > > #define VIDEOTOOLBOX_ESDS_EXTRADATA_PADDING 12 > > +static void videotoolbox_stop(AVCodecContext *avctx); > +static int videotoolbox_start(AVCodecContext *avctx); > + > static void videotoolbox_buffer_release(void *opaque, uint8_t *data) > { > CVPixelBufferRef cv_buffer = (CVImageBufferRef)data; > @@ -350,13 +353,25 @@ static int videotoolbox_common_end_frame(AVCodecContext > *avctx, AVFrame *frame) > int status; > AVVideotoolboxContext *videotoolbox = avctx->hwaccel_context; > VTContext *vtctx = avctx->internal->hwaccel_priv_data; > + int retry; > > av_buffer_unref(&frame->buf[0]); > > if (!videotoolbox->session || !vtctx->bitstream) > return AVERROR_INVALIDDATA; > > - status = videotoolbox_session_decode_frame(avctx); > + for (retry = 0; retry < 2; retry++) { Why retry? > + status = videotoolbox_session_decode_frame(avctx); > + > + if (status == kVTVideoDecoderBadDataErr) { > + av_log(avctx, AV_LOG_DEBUG, "vt decoder got bad data error, > restarting..\n"); > + videotoolbox_stop(avctx); > + videotoolbox_start(avctx); Wouldn't Bad Things happen if the session failed to create for some reason? > + continue; > + } else { > + break; > + } > + } > > if (status) { > av_log(avctx, AV_LOG_ERROR, "Failed to decode frame (%d)\n", status); > @@ -506,7 +521,7 @@ static CMVideoFormatDescriptionRef > videotoolbox_format_desc_create(CMVideoCodecT > return cm_fmt_desc; > } > > -static int videotoolbox_default_init(AVCodecContext *avctx) > +static int videotoolbox_start(AVCodecContext *avctx) > { > AVVideotoolboxContext *videotoolbox = avctx->hwaccel_context; > OSStatus status; > @@ -587,7 +602,12 @@ static int videotoolbox_default_init(AVCodecContext > *avctx) > } > } > > -static void videotoolbox_default_free(AVCodecContext *avctx) > +static int videotoolbox_default_init(AVCodecContext *avctx) > +{ > + return videotoolbox_start(avctx); > +} > + > +static void videotoolbox_stop(AVCodecContext *avctx) > { > AVVideotoolboxContext *videotoolbox = avctx->hwaccel_context; > if (!videotoolbox) > @@ -696,7 +716,7 @@ int av_videotoolbox_default_init2(AVCodecContext *avctx, > AVVideotoolboxContext * > void av_videotoolbox_default_free(AVCodecContext *avctx) > { > > - videotoolbox_default_free(avctx); > + videotoolbox_stop(avctx); > av_freep(&avctx->hwaccel_context); > } > #endif /* CONFIG_VIDEOTOOLBOX */ _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
