pthread: do not touch has_b_frames

Adding the thread count in frame level multithreading to has_b_frames
as an additional delay causes more problems than it solves.
For example inconsistent behaviour during timestamp calculation in
libavformat.
Thread count and frame level multithreading are both set by the user.
If the additional delay caused by frame level multithreading needs
to be considered in the calling code it has all information to take
it into account.
Should it become necessary to calculate a maximum delay inside
libavcodec it should be exported as its own field and not reusing
an existing field.

Based on a patch by Michael Niedermayer.
Signed-off-by: Janne Grunau <janne-libav@jannau.net>

libavcodec/pthread.c

@@ -363,8 +363,7 @@ static int update_context_from_thread(AVCodecContext *dst, AVCodecContext *src,
     }
 
     if (for_user) {
-        dst->coded_frame   = src->coded_frame;
-        dst->has_b_frames += src->thread_count - 1;
+        dst->coded_frame = src->coded_frame;
     } else {
         if (dst->codec->update_thread_context)
             err = dst->codec->update_thread_context(dst, src);
@@ -684,7 +683,6 @@ static void frame_thread_free(AVCodecContext *avctx, int thread_count)
     av_freep(&fctx->threads);
     pthread_mutex_destroy(&fctx->buffer_mutex);
     av_freep(&avctx->thread_opaque);
-    avctx->has_b_frames -= avctx->thread_count - 1;
 }
 
 static int frame_thread_init(AVCodecContext *avctx)

libavcodec/version.h

@@ -21,7 +21,7 @@
 #define AVCODEC_VERSION_H
 
 #define LIBAVCODEC_VERSION_MAJOR 53
-#define LIBAVCODEC_VERSION_MINOR 21
+#define LIBAVCODEC_VERSION_MINOR 22
 #define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \

libavformat/utils.c

@@ -964,11 +964,6 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
     delay= st->codec->has_b_frames;
     presentation_delayed = 0;
 
-    // ignore delay caused by frame threading so that the mpeg2-without-dts
-    // warning will not trigger
-    if (delay && st->codec->active_thread_type&FF_THREAD_FRAME)
-        delay -= st->codec->thread_count-1;
-
     /* XXX: need has_b_frame, but cannot get it if the codec is
         not initialized */
     if (delay &&