fftools/ffmpeg: use the sync queues to handle -frames

Same issues apply to it as to -shortest.

Changes the results of the following tests:
- matroska-flac-extradata-update
  The test reencodes two input FLAC streams into three output FLAC
  streams. The last output stream is limited to 8 frames. The current
  code results in the first two output streams having 12 frames, after
  this commit all three streams have 8 frames and are the same length.
  This new result is better, since it is predictable.
- mkv-1242
  The test streamcopies one video and one audio stream, video is limited
  to 11 frames. The new result shortens the audio stream so that it is
  not longer than the video.

1 files changed, 19 insertions, 5 deletions

diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
index 4281644cfc..f7b5ce347b 100644
--- a/fftools/ffmpeg_opt.c
+++ b/fftools/ffmpeg_opt.c
@@ -2390,6 +2390,7 @@ static int init_complex_filters(void)
 static int setup_sync_queues(OutputFile *of, AVFormatContext *oc, int64_t buf_size_us)
 {
     int nb_av_enc = 0, nb_interleaved = 0;
+    int limit_frames = 0, limit_frames_av_enc = 0;
 
 #define IS_AV_ENC(ost, type)  \
     (ost->encoding_needed && (type == AVMEDIA_TYPE_VIDEO || type == AVMEDIA_TYPE_AUDIO))
@@ -2404,14 +2405,19 @@ static int setup_sync_queues(OutputFile *of, AVFormatContext *oc, int64_t buf_si
 
         nb_interleaved += IS_INTERLEAVED(type);
         nb_av_enc      += IS_AV_ENC(ost, type);
+
+        limit_frames        |=  ost->max_frames < INT64_MAX;
+        limit_frames_av_enc |= (ost->max_frames < INT64_MAX) && IS_AV_ENC(ost, type);
     }
 
-    if (!(nb_interleaved > 1 && of->shortest))
+    if (!((nb_interleaved > 1 && of->shortest) ||
+          (nb_interleaved > 0 && limit_frames)))
         return 0;
 
-    /* if we have more than one encoded audio/video streams, then we
+    /* if we have more than one encoded audio/video streams, or at least
+     * one encoded audio/video stream is frame-limited, then we
      * synchronize them before encoding */
-    if (nb_av_enc > 1) {
+    if ((of->shortest && nb_av_enc > 1) || limit_frames_av_enc) {
         of->sq_encode = sq_alloc(SYNC_QUEUE_FRAMES, buf_size_us);
         if (!of->sq_encode)
             return AVERROR(ENOMEM);
@@ -2423,13 +2429,17 @@ static int setup_sync_queues(OutputFile *of, AVFormatContext *oc, int64_t buf_si
             if (!IS_AV_ENC(ost, type))
                 continue;
 
-            ost->sq_idx_encode = sq_add_stream(of->sq_encode);
+            ost->sq_idx_encode = sq_add_stream(of->sq_encode,
+                                               of->shortest || ost->max_frames < INT64_MAX);
             if (ost->sq_idx_encode < 0)
                 return ost->sq_idx_encode;
 
             ost->sq_frame = av_frame_alloc();
             if (!ost->sq_frame)
                 return AVERROR(ENOMEM);
+
+            if (ost->max_frames != INT64_MAX)
+                sq_limit_frames(of->sq_encode, ost->sq_idx_encode, ost->max_frames);
         }
     }
 
@@ -2447,9 +2457,13 @@ static int setup_sync_queues(OutputFile *of, AVFormatContext *oc, int64_t buf_si
             if (!IS_INTERLEAVED(type))
                 continue;
 
-            ost->sq_idx_mux = sq_add_stream(of->sq_mux);
+            ost->sq_idx_mux = sq_add_stream(of->sq_mux,
+                                            of->shortest || ost->max_frames < INT64_MAX);
             if (ost->sq_idx_mux < 0)
                 return ost->sq_idx_mux;
+
+            if (ost->max_frames != INT64_MAX)
+                sq_limit_frames(of->sq_mux, ost->sq_idx_mux, ost->max_frames);
         }
     }