lavf: allow grouping packets in chunks of a user specified size and duration.

This is similar to MP4Boxs -inter
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/avformat.h

@@ -700,6 +700,9 @@ typedef struct AVStream {
      */
     int stream_identifier;
 
+    int64_t interleaver_chunk_size;
+    int64_t interleaver_chunk_duration;
+
     /**
      * Stream informations used internally by av_find_stream_info()
      */
@@ -1086,6 +1089,22 @@ typedef struct AVFormatContext {
      */
     int audio_preload;
 
+    /**
+     * Max chunk time in microseconds.
+     * Note, not all formats support this and unpredictable things may happen if it is used when not supported.
+     * - encoding: Set by user via AVOptions (NO direct access)
+     * - decoding: unused
+     */
+    int max_chunk_duration;
+
+    /**
+     * Max chunk size in bytes
+     * Note, not all formats support this and unpredictable things may happen if it is used when not supported.
+     * - encoding: Set by user via AVOptions (NO direct access)
+     * - decoding: unused
+     */
+    int max_chunk_size;
+
     /*****************************************************************
      * All fields below this line are not part of the public API. They
      * may not be used outside of libavformat and can be changed and

libavformat/options.c

@@ -117,6 +117,8 @@ static const AVOption options[]={
 {"explode", "abort decoding on error recognition", 0, AV_OPT_TYPE_CONST, {.dbl = FF_ER_EXPLODE }, INT_MIN, INT_MAX, D, "fer"},
 {"fpsprobesize", "number of frames used to probe fps", OFFSET(fps_probe_size), AV_OPT_TYPE_INT, {.dbl = -1}, -1, INT_MAX-1, D},
 {"audio_preload", "microseconds by which audio packets should be interleaved earlier", OFFSET(audio_preload), AV_OPT_TYPE_INT, {.dbl = 0}, 0, INT_MAX-1, E},
+{"chunk_duration", "microseconds for each chunk", OFFSET(max_chunk_duration), AV_OPT_TYPE_INT, {.dbl = 0}, 0, INT_MAX-1, E},
+{"chunk_size", "size in bytes for each chunk", OFFSET(max_chunk_size), AV_OPT_TYPE_INT, {.dbl = 0}, 0, INT_MAX-1, E},
 {NULL},
 };
 

libavformat/utils.c

@@ -3263,10 +3263,14 @@ int av_write_frame(AVFormatContext *s, AVPacket *pkt)
     return ret;
 }
 
+#define CHUNK_START 0x1000
+
 int ff_interleave_add_packet(AVFormatContext *s, AVPacket *pkt,
                               int (*compare)(AVFormatContext *, AVPacket *, AVPacket *))
 {
     AVPacketList **next_point, *this_pktl;
+    AVStream *st= s->streams[pkt->stream_index];
+    int chunked= s->max_chunk_size || s->max_chunk_duration;
 
     this_pktl = av_mallocz(sizeof(AVPacketList));
     if (!this_pktl)
@@ -3276,15 +3280,33 @@ int ff_interleave_add_packet(AVFormatContext *s, AVPacket *pkt,
     av_dup_packet(&this_pktl->pkt);  // duplicate the packet if it uses non-alloced memory
 
     if(s->streams[pkt->stream_index]->last_in_packet_buffer){
-        next_point = &(s->streams[pkt->stream_index]->last_in_packet_buffer->next);
-    }else
+        next_point = &(st->last_in_packet_buffer->next);
+    }else{
         next_point = &s->packet_buffer;
+    }
 
     if(*next_point){
+        if(chunked){
+            uint64_t max= av_rescale_q(s->max_chunk_duration, AV_TIME_BASE_Q, st->time_base);
+            if(   st->interleaver_chunk_size     + pkt->size     <= s->max_chunk_size-1U
+               && st->interleaver_chunk_duration + pkt->duration <= max-1U){
+                st->interleaver_chunk_size     += pkt->size;
+                st->interleaver_chunk_duration += pkt->duration;
+                goto next_non_null;
+            }else{
+                st->interleaver_chunk_size     =
+                st->interleaver_chunk_duration = 0;
+                this_pktl->pkt.flags |= CHUNK_START;
+            }
+        }
+
         if(compare(s, &s->packet_buffer_end->pkt, pkt)){
-            while(!compare(s, &(*next_point)->pkt, pkt)){
+            while(   *next_point
+                  && ((chunked && !((*next_point)->pkt.flags&CHUNK_START))
+                      || !compare(s, &(*next_point)->pkt, pkt))){
                 next_point= &(*next_point)->next;
             }
+            if(*next_point)
                 goto next_non_null;
         }else{
             next_point = &(s->packet_buffer_end->next);

libavformat/version.h

@@ -24,7 +24,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFORMAT_VERSION_MAJOR 53
-#define LIBAVFORMAT_VERSION_MINOR 23
+#define LIBAVFORMAT_VERSION_MINOR 24
 #define LIBAVFORMAT_VERSION_MICRO  0
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \