fftools/ffmpeg: move -stream_loop handling to the demuxer thread

-stream_loop is currently handled by destroying the demuxer thread,
seeking, then recreating it anew. This is very messy and conflicts with
the future goal of moving each major ffmpeg component into its own
thread.

Handle -stream_loop directly in the demuxer thread. Looping requires the
demuxer to know the duration of the file, which takes into account the
duration of the last decoded audio frame (if any). Use a thread message
queue to communicate this information from the main thread to the
demuxer thread.

1 files changed, 20 insertions, 3 deletions

diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index 2a9c34eb93..aa97f35310 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -407,6 +407,11 @@ typedef struct InputStream {
     int got_output;
 } InputStream;
 
+typedef struct LastFrameDuration {
+    int     stream_idx;
+    int64_t duration;
+} LastFrameDuration;
+
 typedef struct InputFile {
     int index;
 
@@ -438,6 +443,11 @@ typedef struct InputFile {
     pthread_t thread;           /* thread reading from this file */
     int non_blocking;           /* reading packets from the thread should not block */
     int thread_queue_size;      /* maximum number of queued packets */
+
+    /* when looping the input file, this queue is used by decoders to report
+     * the last frame duration back to the demuxer thread */
+    AVThreadMessageQueue *audio_duration_queue;
+    int                   audio_duration_queue_size;
 } InputFile;
 
 enum forced_keyframes_const {
@@ -710,11 +720,18 @@ int64_t of_filesize(OutputFile *of);
 AVChapter * const *
 of_get_chapters(OutputFile *of, unsigned int *nb_chapters);
 
+/**
+ * Get next input packet from the demuxer.
+ *
+ * @param pkt the packet is written here when this function returns 0
+ * @return
+ * - 0 when a packet has been read successfully
+ * - 1 when stream end was reached, but the stream is looped;
+ *     caller should flush decoders and read from this demuxer again
+ * - a negative error code on failure
+ */
 int ifile_get_packet(InputFile *f, AVPacket **pkt);
 int init_input_threads(void);
-int init_input_thread(int i);
 void free_input_threads(void);
-void free_input_thread(int i);
-int seek_to_start(InputFile *ifile, AVFormatContext *is);
 
 #endif /* FFTOOLS_FFMPEG_H */