avformat/movenc: support writing iTunes cover image

Fixes https://trac.ffmpeg.org/ticket/2798

This makes movenc handle AV_DISPOSITION_ATTACHED_PIC and write
the associated pictures in iTunes cover atom. This corresponds
to how 'mov' demuxer parses and exposes the cover images when
reading.

Most of the existing track handling loops properly ignore
these 'virtual streams' as MOVTrack->entry is never incremented
for them. However, additional tests are added as needed to ignore
them.

Tested to produce valid output with:
  ffmpeg -i movie.mp4 -i thumb.jpg -disposition:v:1 attached_pic \
         -map 0 -map 1 -c copy movie-with-cover.mp4

The cover image is also copied correctly with:
  ffmpeg -i movie-with-cover.mp4 -map 0 -c copy out.mp4

AtomicParseley says that the attached_pic stream is properly
not visible in the main tracks of the file.
Signed-off-by: Timo Teräs <timo.teras@iki.fi>

libavformat/movenc.c

@@ -142,7 +142,9 @@ static int co64_required(const MOVTrack *track)
 
 static int rtp_hinting_needed(const AVStream *st)
 {
-    /* Add hint tracks for each audio and video stream */
+    /* Add hint tracks for each real audio and video stream */
+    if (st->disposition & AV_DISPOSITION_ATTACHED_PIC)
+        return 0;
     return st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO ||
            st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO;
 }
@@ -3420,6 +3422,51 @@ static int mov_write_int8_metadata(AVFormatContext *s, AVIOContext *pb,
     return size;
 }
 
+static int mov_write_covr(AVIOContext *pb, AVFormatContext *s)
+{
+    MOVMuxContext *mov = s->priv_data;
+    int64_t pos = 0;
+    int i, type;
+
+    for (i = 0; i < s->nb_streams; i++) {
+        MOVTrack *trk = &mov->tracks[i];
+        AVStream *st = s->streams[i];
+
+        if (!(st->disposition & AV_DISPOSITION_ATTACHED_PIC) ||
+            trk->cover_image.size <= 0)
+            continue;
+
+        switch (st->codecpar->codec_id) {
+        case AV_CODEC_ID_MJPEG:
+            type = 0xD;
+            break;
+        case AV_CODEC_ID_PNG:
+            type = 0xE;
+            break;
+        case AV_CODEC_ID_BMP:
+            type = 0x1B;
+            break;
+        default:
+            av_log(s, AV_LOG_ERROR, "unsupported codec_id (0x%x) for cover",
+                   st->codecpar->codec_id);
+            continue;
+        }
+
+        if (!pos) {
+            pos = avio_tell(pb);
+            avio_wb32(pb, 0);
+            ffio_wfourcc(pb, "covr");
+        }
+        avio_wb32(pb, 16 + trk->cover_image.size);
+        ffio_wfourcc(pb, "data");
+        avio_wb32(pb, type);
+        avio_wb32(pb , 0);
+        avio_write(pb, trk->cover_image.data, trk->cover_image.size);
+    }
+
+    return pos ? update_size(pb, pos) : 0;
+}
+
 /* iTunes meta data list */
 static int mov_write_ilst_tag(AVIOContext *pb, MOVMuxContext *mov,
                               AVFormatContext *s)
@@ -3454,6 +3501,7 @@ static int mov_write_ilst_tag(AVIOContext *pb, MOVMuxContext *mov,
     mov_write_int8_metadata  (s, pb, "hdvd",    "hd_video",  1);
     mov_write_int8_metadata  (s, pb, "pgap",    "gapless_playback",1);
     mov_write_int8_metadata  (s, pb, "cpil",    "compilation", 1);
+    mov_write_covr(pb, s);
     mov_write_trkn_tag(pb, mov, s, 0); // track number
     mov_write_trkn_tag(pb, mov, s, 1); // disc number
     mov_write_tmpo_tag(pb, s);
@@ -3951,6 +3999,8 @@ static int mov_write_isml_manifest(AVIOContext *pb, MOVMuxContext *mov, AVFormat
         } else {
             continue;
         }
+        if (st->disposition & AV_DISPOSITION_ATTACHED_PIC)
+            continue;
 
         props = (AVCPBProperties*)av_stream_get_side_data(track->st, AV_PKT_DATA_CPB_PROPERTIES, NULL);
 
@@ -4564,6 +4614,8 @@ static int mov_write_ftyp_tag(AVIOContext *pb, AVFormatContext *s)
 
     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st = s->streams[i];
+        if (st->disposition & AV_DISPOSITION_ATTACHED_PIC)
+            continue;
         if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
             has_video = 1;
         if (st->codecpar->codec_id == AV_CODEC_ID_H264)
@@ -4712,6 +4764,8 @@ static int mov_write_identification(AVIOContext *pb, AVFormatContext *s)
         int video_streams_nb = 0, audio_streams_nb = 0, other_streams_nb = 0;
         for (i = 0; i < s->nb_streams; i++) {
             AVStream *st = s->streams[i];
+            if (st->disposition & AV_DISPOSITION_ATTACHED_PIC)
+                continue;
             if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
                 video_streams_nb++;
             else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO)
@@ -4901,7 +4955,8 @@ static int mov_flush_fragment(AVFormatContext *s, int force)
         int buf_size, moov_size;
 
         for (i = 0; i < mov->nb_streams; i++)
-            if (!mov->tracks[i].entry)
+            if (!mov->tracks[i].entry &&
+                (i >= s->nb_streams || !(s->streams[i]->disposition & AV_DISPOSITION_ATTACHED_PIC)))
                 break;
         /* Don't write the initial moov unless all tracks have data */
         if (i < mov->nb_streams && !force)
@@ -5480,13 +5535,34 @@ static int mov_write_subtitle_end_packet(AVFormatContext *s,
 
 static int mov_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
+    MOVMuxContext *mov = s->priv_data;
+    MOVTrack *trk;
+    AVStream *st;
+
     if (!pkt) {
         mov_flush_fragment(s, 1);
         return 1;
+    }
+
+    st = s->streams[pkt->stream_index];
+    trk = &mov->tracks[pkt->stream_index];
+
+    if (st->disposition & AV_DISPOSITION_ATTACHED_PIC) {
+        int ret;
+
+        if (st->nb_frames >= 1) {
+            if (st->nb_frames == 1)
+                av_log(s, AV_LOG_WARNING, "Got more than one picture in stream %d,"
+                       " ignoring.\n", pkt->stream_index);
+            return 0;
+        }
+
+        if ((ret = av_packet_ref(&trk->cover_image, pkt)) < 0)
+            return ret;
+
+        return 0;
     } else {
         int i;
-        MOVMuxContext *mov = s->priv_data;
-        MOVTrack *trk = &mov->tracks[pkt->stream_index];
 
         if (!pkt->size)
             return mov_write_single_packet(s, pkt); /* Passthrough. */
@@ -5733,7 +5809,8 @@ static void enable_tracks(AVFormatContext *s)
         AVStream *st = s->streams[i];
 
         if (st->codecpar->codec_type <= AVMEDIA_TYPE_UNKNOWN ||
-            st->codecpar->codec_type >= AVMEDIA_TYPE_NB)
+            st->codecpar->codec_type >= AVMEDIA_TYPE_NB ||
+            st->disposition & AV_DISPOSITION_ATTACHED_PIC)
             continue;
 
         if (first[st->codecpar->codec_type] < 0)
@@ -5776,6 +5853,7 @@ static void mov_free(AVFormatContext *s)
             av_freep(&mov->tracks[i].par);
         av_freep(&mov->tracks[i].cluster);
         av_freep(&mov->tracks[i].frag_info);
+        av_packet_unref(&mov->tracks[i].cover_image);
 
         if (mov->tracks[i].vos_len)
             av_freep(&mov->tracks[i].vos_data);

libavformat/movenc.h

@@ -132,6 +132,7 @@ typedef struct MOVTrack {
     uint32_t    default_size;
 
     HintSampleQueue sample_queue;
+    AVPacket cover_image;
 
     AVIOContext *mdat_buf;
     int64_t     data_offset;