No h264 hwaccel knows about views. They all build the accelerator's picture list from short_ref and long_ref and skip pictures whose H264Picture.reference is 0 -- see fill_vaapi_ReferenceFrames() and its equivalents in the vdpau, dxva2, nvdec and vulkan code.
An inter-view reference is in neither list, and reference == 0 is normal for it, because inter_view_flag makes a picture available for inter-view prediction independently of whether it is a temporal reference. The per-slice reference list is filled from sl->ref_list[] regardless, so a dependent view slice would name a surface the accelerator was never given. Decode the base view only and log a warning, rather than submit that. Signed-off-by: Dom Cobley <[email protected]> --- libavcodec/h264_slice.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c index 3217e43205..81c275f9c8 100644 --- a/libavcodec/h264_slice.c +++ b/libavcodec/h264_slice.c @@ -994,6 +994,19 @@ static int setup_multiview(H264Context *h, const SPS *mvc_sps) return AVERROR_BUG; } + /* No hwaccel knows about views. They all build the accelerator's picture + * list from short_ref/long_ref, skipping anything with reference == 0, while + * an inter-view reference lives in sl->ref_list[] alone and need not be a + * temporal reference at all. A dependent view slice would therefore point at + * a surface the accelerator was never told about. Decode the base view only + * rather than submit that. */ + if (views_active_output != 1 && h->avctx->hwaccel) { + av_log(h->avctx, AV_LOG_WARNING, + "Multiview decoding is not supported with hardware acceleration; " + "decoding the base view only.\n"); + return 0; + } + highest_view = av_log2(views_active_output); if (highest_view >= H264_MAX_MVC_VIEWS) { av_log(h->avctx, AV_LOG_ERROR, "Too many views requested: %x\n", -- 2.53.0 _______________________________________________ ffmpeg-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
