[FFmpeg-devel] [PATCH] avcodec/videotoolboxenc: don't wait when flushing data

[zhilizhao]

> On Aug 27, 2020, at 10:53 AM, Steven Liu <lq at chinaffmpeg.org> wrote:
> 
> From: Tian Qi <tianqi at kuaishou.com>
> 
> because there is run in thread mode, few times will block
> the workflow at the wait, so check the status is flushing data,
> don't wait when flushing data.
> 
> Signed-off-by: Tian Qi <tianqi at kuaishou.com>
> Signed-off-by: Steven Liu <lq at chinaffmpeg.org>
> ---
> libavcodec/videotoolboxenc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/videotoolboxenc.c b/libavcodec/videotoolboxenc.c
> index e89cfaeed8..f9626be18f 100644
> --- a/libavcodec/videotoolboxenc.c
> +++ b/libavcodec/videotoolboxenc.c
> @@ -292,7 +292,7 @@ static int vtenc_q_pop(VTEncContext *vtctx, bool wait, CMSampleBufferRef *buf, E
>         return 0;
>     }
> 
> -    while (!vtctx->q_head && !vtctx->async_error && wait) {
> +    while (!vtctx->q_head && !vtctx->async_error && wait && !vtctx->flushing) {
>         pthread_cond_wait(&vtctx->cv_sample_sent, &vtctx->lock);
>     }

I’m not familar with the code. I have some questions:
1. The commit message doesn’t give a detailed description of the real issue.

2. vtctx->flushing is modified without holding the lock, which is questionable.
And there is no cond_signal, how does it work?

> 
> @@ -308,6 +308,7 @@ static int vtenc_q_pop(VTEncContext *vtctx, bool wait, CMSampleBufferRef *buf, E
>         vtctx->q_tail = NULL;
>     }
> 
> +    vtctx->frame_ct_out++;

Looks like this modification doesn’t belong to the patch.

>     pthread_mutex_unlock(&vtctx->lock);
> 
>     *buf = info->cm_buffer;
> @@ -319,7 +320,6 @@ static int vtenc_q_pop(VTEncContext *vtctx, bool wait, CMSampleBufferRef *buf, E
>     }
>     av_free(info);
> 
> -    vtctx->frame_ct_out++;
> 
>     return 0;
> }
> -- 
> 2.25.0
> 
> 
> 
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