[FFmpeg-devel] [PATCH 3/3] h264: Run VLC init under pthread_once

[Matt Oliver]

On 8 October 2015 at 02:39, Derek Buitenhuis <derek.buitenhuis at gmail.com>
wrote:

> This makes the h.264 decoder threadsafe to initialize.
>
> Signed-off-by: Derek Buitenhuis <derek.buitenhuis at gmail.com>
> ---
>  libavcodec/h264.c |  7 ++++++-
>  libavcodec/h264.h | 10 ++++++++++
>  2 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/h264.c b/libavcodec/h264.c
> index 3209c9c..27a1d32 100644
> --- a/libavcodec/h264.c
> +++ b/libavcodec/h264.c
> @@ -657,7 +657,11 @@ av_cold int ff_h264_decode_init(AVCodecContext *avctx)
>      if (!avctx->has_b_frames)
>          h->low_delay = 1;
>
> -    ff_h264_decode_init_vlc();
> +    ret = pthread_once(&ff_h264_vlc_init, &ff_h264_decode_init_vlc);
> +    if (ret != 0) {
> +        av_log(avctx, AV_LOG_ERROR, "pthread_once has failed.");
> +        return AVERROR_UNKNOWN;
> +    }
>
>      if (avctx->codec_id == AV_CODEC_ID_H264) {
>          if (avctx->ticks_per_frame == 1) {
> @@ -1993,6 +1997,7 @@ AVCodec ff_h264_decoder = {
>      .capabilities          = /*AV_CODEC_CAP_DRAW_HORIZ_BAND |*/
> AV_CODEC_CAP_DR1 |
>                               AV_CODEC_CAP_DELAY |
> AV_CODEC_CAP_SLICE_THREADS |
>                               AV_CODEC_CAP_FRAME_THREADS,
> +    .caps_internal         = FF_CODEC_CAP_INIT_THREADSAFE,
>      .flush                 = flush_dpb,
>      .init_thread_copy      =
> ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
>      .update_thread_context =
> ONLY_IF_THREADS_ENABLED(ff_h264_update_thread_context),
> diff --git a/libavcodec/h264.h b/libavcodec/h264.h
> index 769abda..c5119f9 100644
> --- a/libavcodec/h264.h
> +++ b/libavcodec/h264.h
> @@ -43,6 +43,14 @@
>  #include "rectangle.h"
>  #include "videodsp.h"
>
> +#if HAVE_PTHREADS
> +#   include <pthread.h>
> +#elif HAVE_OS2THREADS
> +#   include "compat/os2threads.h"
> +#elif HAVE_W32THREADS
> +#   include "compat/w32pthreads.h"
> +#endif
> +
>

Couldnt all the above if/includes be simplified by just using a single
include libavutil/thread.h (which has all the above checks in it.


>  #define H264_MAX_PICTURE_COUNT 36
>  #define H264_MAX_THREADS       32
>
> @@ -931,6 +939,8 @@ int ff_h264_check_intra_pred_mode(const H264Context
> *h, H264SliceContext *sl,
>  void ff_h264_hl_decode_mb(const H264Context *h, H264SliceContext *sl);
>  int ff_h264_decode_extradata(H264Context *h, const uint8_t *buf, int
> size);
>  int ff_h264_decode_init(AVCodecContext *avctx);
> +
> +static pthread_once_t ff_h264_vlc_init = PTHREAD_ONCE_INIT;
>  void ff_h264_decode_init_vlc(void);
>
>  /**
> --
> 1.8.3.1
>
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