[vlc-devel] [PATCH] codec: avcodec: no FRAME threading on unknown/low framerate

[Francois Cartegnie]

fixes always late frames due to threading delay
---
 modules/codec/avcodec/video.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/modules/codec/avcodec/video.c b/modules/codec/avcodec/video.c
index b2aee8ea88..87be13e88c 100644
--- a/modules/codec/avcodec/video.c
+++ b/modules/codec/avcodec/video.c
@@ -460,12 +460,12 @@ static int OpenVideoCodec( decoder_t *p_dec )
     cc_Init( &p_sys->cc );
 
     set_video_color_settings( &p_dec->fmt_in.video, ctx );
-    if( p_dec->fmt_in.video.i_frame_rate_base &&
-        p_dec->fmt_in.video.i_frame_rate &&
+
+    if( p_dec->fmt_in.video.i_frame_rate_base == 0 ||
         (double) p_dec->fmt_in.video.i_frame_rate /
                  p_dec->fmt_in.video.i_frame_rate_base < 6 )
     {
-        /* !warn: this disables any threading */
+        /* this disables FF_THREAD_FRAME */
         ctx->flags |= AV_CODEC_FLAG_LOW_DELAY;
     }
 
@@ -603,7 +603,8 @@ int InitVideoDec( vlc_object_t *obj )
         if( i_thread_count > 1 )
             i_thread_count++;
 
-        //FIXME: take in count the decoding time
+        /* FIXME: take in count the decoding time
+         * Frame threading introduces latency */
 #if VLC_WINSTORE_APP
         i_thread_count = __MIN( i_thread_count, 6 );
 #else
@@ -635,6 +636,14 @@ int InitVideoDec( vlc_object_t *obj )
             break;
     }
 
+    if( p_context->flags |= AV_CODEC_FLAG_LOW_DELAY )
+    {
+        /* LOW_DELAY already disables threading internally
+         * THREAD_FRAME, by we want it explicit for conditional handling
+         * in our code */
+        p_context->thread_type &= ~FF_THREAD_FRAME;
+    }
+
     if( p_context->thread_type & FF_THREAD_FRAME )
         p_dec->i_extra_picture_buffers = 2 * p_context->thread_count;
 
-- 
2.14.4