From b84675d63aaede8f6944b901250a10456c5477e6 Mon Sep 17 00:00:00 2001 From: wm4 Date: Tue, 8 Sep 2015 19:42:22 +0200 Subject: mmaldec: hack against buffering problems on broken input I can't come up with a nice way to handle this. It's hard to keep the lock-stepped input/output in this case. You can't predict whether the MMAL decoder will output a picture (because it's asynchronous), so you have to assume in general that any packet could produce 0 or 1 frames. You can't continue to write input packets to the decoder, because then you might get too many output frames, which you can't get rid of because the lavc decoding API does not allow the decoder to return an output frame without consuming an input frame (except when flushing). The ideal fix is a M:N decoding API (preferably asynchronous), which would make this code potentially much cleaner. For now, this hack will do. Signed-off-by: Luca Barbato --- libavcodec/mmaldec.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'libavcodec') diff --git a/libavcodec/mmaldec.c b/libavcodec/mmaldec.c index 64e5da6324..374bd2f30c 100644 --- a/libavcodec/mmaldec.c +++ b/libavcodec/mmaldec.c @@ -644,12 +644,21 @@ static int ffmmal_read_frame(AVCodecContext *avctx, AVFrame *frame, int *got_fra // We also wait if we sent eos, but didn't receive it yet (think of decoding // stream with a very low number of frames). if (ctx->frames_output || ctx->packets_sent > MAX_DELAYED_FRAMES || ctx->eos_sent) { - buffer = mmal_queue_wait(ctx->queue_decoded_frames); + // MMAL will ignore broken input packets, which means the frame we + // expect here may never arrive. Dealing with this correctly is + // complicated, so here's a hack to avoid that it freezes forever + // in this unlikely situation. + buffer = mmal_queue_timedwait(ctx->queue_decoded_frames, 100); + if (!buffer) { + av_log(avctx, AV_LOG_ERROR, "Did not get output frame from MMAL.\n"); + ret = AVERROR_UNKNOWN; + goto done; + } } else { buffer = mmal_queue_get(ctx->queue_decoded_frames); + if (!buffer) + goto done; } - if (!buffer) - goto done; ctx->eos_received |= !!(buffer->flags & MMAL_BUFFER_HEADER_FLAG_EOS); if (ctx->eos_received) -- cgit v1.2.3