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.

5 files changed, 58 insertions, 26 deletions

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 9b6bb3d759..8ab8aee711 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -3478,12 +3478,6 @@ static int need_output(void)
 
         if (ost->finished || of_finished(of))
             continue;
-        if (ost->frame_number >= ost->max_frames) {
-            int j;
-            for (j = 0; j < of->ctx->nb_streams; j++)
-                close_output_stream(output_streams[of->ost_index + j]);
-            continue;
-        }
 
         return 1;
     }
diff --git a/fftools/ffmpeg_mux.c b/fftools/ffmpeg_mux.c
index 641bdb98b0..56444770bf 100644
--- a/fftools/ffmpeg_mux.c
+++ b/fftools/ffmpeg_mux.c
@@ -237,19 +237,11 @@ void of_submit_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost)
 
     if (pkt) {
         /*
-         * Audio encoders may split the packets --  #frames in != #packets out.
-         * But there is no reordering, so we can limit the number of output packets
-         * by simply dropping them here.
          * Counting encoded video frames needs to be done separately because of
          * reordering, see do_video_out().
          */
-        if (!(st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && ost->encoding_needed)) {
-            if (ost->frame_number >= ost->max_frames) {
-                av_packet_unref(pkt);
-                return;
-            }
+        if (!(st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && ost->encoding_needed))
             ost->frame_number++;
-        }
     }
 
     if (of->mux->header_written) {
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);
         }
     }
 
diff --git a/fftools/sync_queue.c b/fftools/sync_queue.c
index ab654ca790..3143d12cf1 100644
--- a/fftools/sync_queue.c
+++ b/fftools/sync_queue.c
@@ -34,8 +34,12 @@ typedef struct SyncQueueStream {
 
     /* stream head: largest timestamp seen */
     int64_t          head_ts;
+    int              limiting;
     /* no more frames will be sent for this stream */
     int              finished;
+
+    uint64_t         frames_sent;
+    uint64_t         frames_max;
 } SyncQueueStream;
 
 struct SyncQueue {
@@ -86,7 +90,7 @@ static void finish_stream(SyncQueue *sq, unsigned int stream_idx)
 
     st->finished = 1;
 
-    if (st->head_ts != AV_NOPTS_VALUE) {
+    if (st->limiting && st->head_ts != AV_NOPTS_VALUE) {
         /* check if this stream is the new finished head */
         if (sq->head_finished_stream < 0 ||
             av_compare_ts(st->head_ts, st->tb,
@@ -121,7 +125,7 @@ static void queue_head_update(SyncQueue *sq)
          * the queue head */
         for (unsigned int i = 0; i < sq->nb_streams; i++) {
             SyncQueueStream *st = &sq->streams[i];
-            if (st->head_ts == AV_NOPTS_VALUE)
+            if (st->limiting && st->head_ts == AV_NOPTS_VALUE)
                 return;
         }
 
@@ -132,7 +136,7 @@ static void queue_head_update(SyncQueue *sq)
     for (unsigned int i = 0; i < sq->nb_streams; i++) {
         SyncQueueStream *st_head  = &sq->streams[sq->head_stream];
         SyncQueueStream *st_other = &sq->streams[i];
-        if (st_other->head_ts != AV_NOPTS_VALUE &&
+        if (st_other->limiting && st_other->head_ts != AV_NOPTS_VALUE &&
             av_compare_ts(st_other->head_ts, st_other->tb,
                           st_head->head_ts,  st_head->tb) < 0)
             sq->head_stream = i;
@@ -159,7 +163,8 @@ static void stream_update_ts(SyncQueue *sq, unsigned int stream_idx, int64_t ts)
         finish_stream(sq, stream_idx);
 
     /* update the overall head timestamp if it could have changed */
-    if (sq->head_stream < 0 || sq->head_stream == stream_idx)
+    if (st->limiting &&
+        (sq->head_stream < 0 || sq->head_stream == stream_idx))
         queue_head_update(sq);
 }
 
@@ -262,6 +267,10 @@ int sq_send(SyncQueue *sq, unsigned int stream_idx, SyncQueueFrame frame)
 
     stream_update_ts(sq, stream_idx, ts);
 
+    st->frames_sent++;
+    if (st->frames_sent >= st->frames_max)
+        finish_stream(sq, stream_idx);
+
     return 0;
 }
 
@@ -339,7 +348,7 @@ int sq_receive(SyncQueue *sq, int stream_idx, SyncQueueFrame frame)
     return ret;
 }
 
-int sq_add_stream(SyncQueue *sq)
+int sq_add_stream(SyncQueue *sq, int limiting)
 {
     SyncQueueStream *tmp, *st;
 
@@ -360,6 +369,8 @@ int sq_add_stream(SyncQueue *sq)
      * streams forever; cf. overflow_heartbeat() */
     st->tb      = (AVRational){ 1, 1 };
     st->head_ts = AV_NOPTS_VALUE;
+    st->frames_max = UINT64_MAX;
+    st->limiting   = limiting;
 
     return sq->nb_streams++;
 }
@@ -379,6 +390,18 @@ void sq_set_tb(SyncQueue *sq, unsigned int stream_idx, AVRational tb)
     st->tb = tb;
 }
 
+void sq_limit_frames(SyncQueue *sq, unsigned int stream_idx, uint64_t frames)
+{
+    SyncQueueStream *st;
+
+    av_assert0(stream_idx < sq->nb_streams);
+    st = &sq->streams[stream_idx];
+
+    st->frames_max = frames;
+    if (st->frames_sent >= st->frames_max)
+        finish_stream(sq, stream_idx);
+}
+
 SyncQueue *sq_alloc(enum SyncQueueType type, int64_t buf_size_us)
 {
     SyncQueue *sq = av_mallocz(sizeof(*sq));
diff --git a/fftools/sync_queue.h b/fftools/sync_queue.h
index e08780b7bf..3f823ff0d9 100644
--- a/fftools/sync_queue.h
+++ b/fftools/sync_queue.h
@@ -51,11 +51,13 @@ void       sq_free(SyncQueue **sq);
 /**
  * Add a new stream to the sync queue.
  *
+ * @param limiting whether the stream is limiting, i.e. no other stream can be
+ *                 longer than this one
  * @return
  * - a non-negative stream index on success
  * - a negative error code on error
  */
-int sq_add_stream(SyncQueue *sq);
+int sq_add_stream(SyncQueue *sq, int limiting);
 
 /**
  * Set the timebase for the stream with index stream_idx. Should be called
@@ -64,6 +66,13 @@ int sq_add_stream(SyncQueue *sq);
 void sq_set_tb(SyncQueue *sq, unsigned int stream_idx, AVRational tb);
 
 /**
+ * Limit the number of output frames for stream with index stream_idx
+ * to max_frames.
+ */
+void sq_limit_frames(SyncQueue *sq, unsigned int stream_idx,
+                     uint64_t max_frames);
+
+/**
  * Submit a frame for the stream with index stream_idx.
  *
  * On success, the sync queue takes ownership of the frame and will reset the