[FFmpeg-devel] [PATCH] pthread_frame: attempt to get frame to reduce latency

[Jianhui Dai]

Avoid constant N frames latency in video streaming.

Signed-off-by: Jianhui Dai <jianhui.j.dai at intel.com>
---
 libavcodec/pthread_frame.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/libavcodec/pthread_frame.c b/libavcodec/pthread_frame.c
index b5bd494474..aeb42800ef 100644
--- a/libavcodec/pthread_frame.c
+++ b/libavcodec/pthread_frame.c
@@ -130,11 +130,6 @@ typedef struct FrameThreadContext {
 
     int next_decoding;             ///< The next context to submit a packet to.
     int next_finished;             ///< The next context to return output from.
-
-    int delaying;                  /**<
-                                    * Set for the first N packets, where N is the number of threads.
-                                    * While it is set, ff_thread_en/decode_frame won't return any results.
-                                    */
 } FrameThreadContext;
 
 #define THREAD_SAFE_CALLBACKS(avctx) \
@@ -492,14 +487,8 @@ int ff_thread_decode_frame(AVCodecContext *avctx,
     if (err)
         goto finish;
 
-    /*
-     * If we're still receiving the initial packets, don't return a frame.
-     */
-
-    if (fctx->next_decoding > (avctx->thread_count-1-(avctx->codec_id == AV_CODEC_ID_FFV1)))
-        fctx->delaying = 0;
-
-    if (fctx->delaying) {
+    if (((fctx->next_decoding + 1) % avctx->thread_count) != finished &&
+        atomic_load(&fctx->threads[finished].state) != STATE_INPUT_READY) {
         *got_picture_ptr=0;
         if (avpkt->size) {
             err = avpkt->size;
@@ -763,7 +752,6 @@ int ff_frame_thread_init(AVCodecContext *avctx)
     pthread_cond_init(&fctx->async_cond, NULL);
 
     fctx->async_lock = 1;
-    fctx->delaying = 1;
 
     for (i = 0; i < thread_count; i++) {
         AVCodecContext *copy = av_malloc(sizeof(AVCodecContext));
@@ -854,7 +842,6 @@ void ff_thread_flush(AVCodecContext *avctx)
     }
 
     fctx->next_decoding = fctx->next_finished = 0;
-    fctx->delaying = 1;
     fctx->prev_thread = NULL;
     for (i = 0; i < avctx->thread_count; i++) {
         PerThreadContext *p = &fctx->threads[i];
-- 
2.17.1