idroqdec: set AVFMTCTX_NOHEADER and create streams as they occur.

This fixes demuxing of file where the first packet is not audio. Such files
are generated by our idroq muxer. It also fixes demuxing of audio only
idroq files.

libavformat/idroqdec.c

@@ -44,6 +44,7 @@
 
 typedef struct RoqDemuxContext {
 
+    int frame_rate;
     int width;
     int height;
     int audio_channels;
@@ -70,29 +71,21 @@ static int roq_read_header(AVFormatContext *s,
 {
     RoqDemuxContext *roq = s->priv_data;
     AVIOContext *pb = s->pb;
-    int framerate;
-    AVStream *st;
     unsigned char preamble[RoQ_CHUNK_PREAMBLE_SIZE];
 
     /* get the main header */
     if (avio_read(pb, preamble, RoQ_CHUNK_PREAMBLE_SIZE) !=
         RoQ_CHUNK_PREAMBLE_SIZE)
         return AVERROR(EIO);
-    framerate = AV_RL16(&preamble[6]);
+    roq->frame_rate = AV_RL16(&preamble[6]);
 
     /* init private context parameters */
     roq->width = roq->height = roq->audio_channels = roq->video_pts =
     roq->audio_frame_count = 0;
     roq->audio_stream_index = -1;
+    roq->video_stream_index = -1;
 
-    st = avformat_new_stream(s, NULL);
-    if (!st)
-        return AVERROR(ENOMEM);
-    avpriv_set_pts_info(st, 63, 1, framerate);
-    roq->video_stream_index = st->index;
-    st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
-    st->codec->codec_id = CODEC_ID_ROQ;
-    st->codec->codec_tag = 0;  /* no fourcc */
+    s->ctx_flags |= AVFMTCTX_NOHEADER;
 
     return 0;
 }
@@ -128,8 +121,16 @@ static int roq_read_packet(AVFormatContext *s,
         switch (chunk_type) {
 
         case RoQ_INFO:
-            if (!roq->width || !roq->height) {
-                AVStream *st = s->streams[roq->video_stream_index];
+            if (roq->video_stream_index == -1) {
+                AVStream *st = avformat_new_stream(s, NULL);
+                if (!st)
+                    return AVERROR(ENOMEM);
+                avpriv_set_pts_info(st, 63, 1, roq->frame_rate);
+                roq->video_stream_index = st->index;
+                st->codec->codec_type   = AVMEDIA_TYPE_VIDEO;
+                st->codec->codec_id     = CODEC_ID_ROQ;
+                st->codec->codec_tag    = 0;  /* no fourcc */
+
                 if (avio_read(pb, preamble, RoQ_CHUNK_PREAMBLE_SIZE) != RoQ_CHUNK_PREAMBLE_SIZE)
                     return AVERROR(EIO);
                 st->codec->width  = roq->width  = AV_RL16(preamble);