On Mon, 25 Sep 2017 17:36:30 -0700
Aman Gupta <ffm...@tmm1.net> wrote:
> From: Aman Gupta <a...@tmm1.net>
>
> If the VideoToolbox session needs to be restarted, and
> videotoolbox_start() fails for some reason (for instance, if the video
> is interlaced and the decoder is running on iOS), avcodec will return
> AVERROR_EXTERNAL. This can be used by the API user to switch to another
> decoder.
> ---
> libavcodec/vda_vt_internal.h | 6 ++++++
> libavcodec/videotoolbox.c | 45
> +++++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/vda_vt_internal.h b/libavcodec/vda_vt_internal.h
> index e55a813899..49c91791ee 100644
> --- a/libavcodec/vda_vt_internal.h
> +++ b/libavcodec/vda_vt_internal.h
> @@ -47,6 +47,12 @@ typedef struct VTContext {
> // Non-NULL if the new hwaccel API is used. This is only a separate
> struct
> // to ease compatibility with the old API.
> struct AVVideotoolboxContext *vt_ctx;
> +
> + // Current H264 parameters (used to trigger decoder restart on SPS
> changes).
> + uint8_t *sps;
> + uint32_t sps_len;
> + unsigned int sps_capa;
> + bool reconfig_needed;
> } VTContext;
>
> int ff_videotoolbox_alloc_frame(AVCodecContext *avctx, AVFrame *frame);
> diff --git a/libavcodec/videotoolbox.c b/libavcodec/videotoolbox.c
> index f56ab1f8c9..6c8477c2ce 100644
> --- a/libavcodec/videotoolbox.c
> +++ b/libavcodec/videotoolbox.c
> @@ -41,6 +41,9 @@
>
> #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;
> @@ -148,6 +151,33 @@ int ff_videotoolbox_h264_start_frame(AVCodecContext
> *avctx,
> return 0;
> }
>
> +static int videotoolbox_h264_decode_params(AVCodecContext *avctx,
> + const uint8_t *buffer,
> + uint32_t size)
> +{
> + VTContext *vtctx = avctx->internal->hwaccel_priv_data;
> + H264Context *h = avctx->priv_data;
> +
> + if (h->is_avc == 1)
> + return 0;
Should that matter?
> + switch (buffer[0] & 0x1f) {
> + case H264_NAL_SPS:
> + if (!vtctx->sps || vtctx->sps_len != size || memcmp(buffer,
> vtctx->sps, size) != 0) {
> + vtctx->sps = av_fast_realloc(vtctx->sps, &vtctx->sps_capa,
> size);
> + if (vtctx->sps)
> + memcpy(vtctx->sps, buffer, size);
> + if (vtctx->sps_len)
> + vtctx->reconfig_needed = true;
> + vtctx->sps_len = size;
> + }
> + break;
> + }
To be honest, I think just rebuilding the avcc and testing for a change
would be simpler. Unless there's a good reason not to reinit when only
the PPS changes.
Might also make sense to pass the NAL type as parameter to the
AVHWAccel function?
Otherwise I'm fine with it.
> + // pass-through new PPS to the decoder
> + return ff_videotoolbox_h264_decode_slice(avctx, buffer, size);
> +}
> +
> int ff_videotoolbox_h264_decode_slice(AVCodecContext *avctx,
> const uint8_t *buffer,
> uint32_t size)
> @@ -180,6 +210,7 @@ int ff_videotoolbox_uninit(AVCodecContext *avctx)
> VTContext *vtctx = avctx->internal->hwaccel_priv_data;
> if (vtctx) {
> av_freep(&vtctx->bitstream);
> + av_freep(&vtctx->sps);
> if (vtctx->frame)
> CVPixelBufferRelease(vtctx->frame);
> }
> @@ -419,7 +450,16 @@ static int videotoolbox_common_end_frame(AVCodecContext
> *avctx, AVFrame *frame)
> AVVideotoolboxContext *videotoolbox = videotoolbox_get_context(avctx);
> VTContext *vtctx = avctx->internal->hwaccel_priv_data;
>
> - if (!videotoolbox->session || !vtctx->bitstream)
> + if (vtctx->reconfig_needed == true) {
> + vtctx->reconfig_needed = false;
> + av_log(avctx, AV_LOG_VERBOSE, "VideoToolbox decoder needs reconfig,
> restarting..\n");
> + videotoolbox_stop(avctx);
> + if (videotoolbox_start(avctx) != 0) {
> + return AVERROR_EXTERNAL;
> + }
> + }
> +
> + if (!videotoolbox->session || !vtctx->bitstream ||
> !vtctx->bitstream_size)
> return AVERROR_INVALIDDATA;
>
> status = videotoolbox_session_decode_frame(avctx);
> @@ -432,9 +472,11 @@ static int videotoolbox_common_end_frame(AVCodecContext
> *avctx, AVFrame *frame)
> break;
> case kVTVideoDecoderMalfunctionErr:
> error = "decoder malfunction";
> + vtctx->reconfig_needed = true;
> break;
> case kVTInvalidSessionErr:
> error = "invalid session";
> + vtctx->reconfig_needed = true;
> break;
> default:
> error = "unknown";
> @@ -824,6 +866,7 @@ AVHWAccel ff_h264_videotoolbox_hwaccel = {
> .alloc_frame = ff_videotoolbox_alloc_frame,
> .start_frame = ff_videotoolbox_h264_start_frame,
> .decode_slice = ff_videotoolbox_h264_decode_slice,
> + .decode_params = videotoolbox_h264_decode_params,
> .end_frame = videotoolbox_h264_end_frame,
> .init = videotoolbox_common_init,
> .uninit = videotoolbox_uninit,
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