[FFmpeg-devel] [PATCH v2] ogg/vorbis: implement header packet skip in chained ogg bitstreams.

Romain Beauxis romain.beauxis at gmail.com
Wed Jun 4 19:58:52 EEST 2025


This is a redo of 574f634e49847e2225ee50013afebf0de03ef013 using a flat
memory storage for the extradata.

PR review comments addressed:
* Use flat memory bytestream
* Re-use existing xiph extradata layout

---
 libavcodec/vorbisdec.c                     | 42 ++++++++---
 libavformat/oggparsevorbis.c               | 83 +++++++++++++++++++++-
 tests/ref/fate/ogg-vorbis-chained-meta.txt |  3 -
 3 files changed, 114 insertions(+), 14 deletions(-)

diff --git a/libavcodec/vorbisdec.c b/libavcodec/vorbisdec.c
index adbd726183..84879462a1 100644
--- a/libavcodec/vorbisdec.c
+++ b/libavcodec/vorbisdec.c
@@ -1778,11 +1778,40 @@ static int vorbis_decode_frame(AVCodecContext *avctx, AVFrame *frame,
     GetBitContext *gb = &vc->gb;
     float *channel_ptrs[255];
     int i, len, ret;
+    size_t new_extradata_size;
+    const uint8_t *new_extradata;
+    const uint8_t *header_start[3];
+    int header_len[3] = {0, 0, 0};
+    const uint8_t *header;
+    int header_size = 0;
+    const uint8_t *comment;
+    int comment_size = 0;
+    const uint8_t *setup;
+    int setup_size = 0;
 
     ff_dlog(NULL, "packet length %d \n", buf_size);
 
-    if (*buf == 1 && buf_size > 7) {
-        if ((ret = init_get_bits8(gb, buf + 1, buf_size - 1)) < 0)
+    new_extradata = av_packet_get_side_data(avpkt, AV_PKT_DATA_NEW_EXTRADATA,
+                        &new_extradata_size);
+
+    if (new_extradata) {
+        ret = avpriv_split_xiph_headers(new_extradata, new_extradata_size,
+                                        30, header_start, header_len);
+        if (ret < 0)
+            return ret;
+
+        header = header_start[0];
+        header_size = header_len[0];
+
+        comment = header_start[1];
+        comment_size = header_len[1];
+
+        setup = header_start[2];
+        setup_size = header_len[2];
+    }
+
+    if (header_size > 7 && *header == 1) {
+        if ((ret = init_get_bits8(gb, header + 1, header_size - 1)) < 0)
             return ret;
 
         vorbis_free(vc);
@@ -1801,16 +1830,14 @@ static int vorbis_decode_frame(AVCodecContext *avctx, AVFrame *frame,
         }
 
         avctx->sample_rate = vc->audio_samplerate;
-        return buf_size;
     }
 
-    if (*buf == 3 && buf_size > 7) {
+    if (comment_size > 7 && *comment == 3) {
         av_log(avctx, AV_LOG_DEBUG, "Ignoring comment header\n");
-        return buf_size;
     }
 
-    if (*buf == 5 && buf_size > 7 && vc->channel_residues && !vc->modes) {
-        if ((ret = init_get_bits8(gb, buf + 1, buf_size - 1)) < 0)
+    if (setup_size > 7 && *setup == 5 && vc->channel_residues && !vc->modes) {
+        if ((ret = init_get_bits8(gb, setup + 1, setup_size - 1)) < 0)
             return ret;
 
         if ((ret = vorbis_parse_setup_hdr(vc))) {
@@ -1818,7 +1845,6 @@ static int vorbis_decode_frame(AVCodecContext *avctx, AVFrame *frame,
             vorbis_free(vc);
             return ret;
         }
-        return buf_size;
     }
 
     if (!vc->channel_residues || !vc->modes) {
diff --git a/libavformat/oggparsevorbis.c b/libavformat/oggparsevorbis.c
index 62cc2da6de..7859ec5a51 100644
--- a/libavformat/oggparsevorbis.c
+++ b/libavformat/oggparsevorbis.c
@@ -215,6 +215,12 @@ struct oggvorbis_private {
     AVVorbisParseContext *vp;
     int64_t final_pts;
     int final_duration;
+    uint8_t *header;
+    int header_size;
+    uint8_t *comment;
+    int comment_size;
+    uint8_t *setup;
+    int setup_size;
 };
 
 static int fixup_vorbis_headers(AVFormatContext *as,
@@ -260,6 +266,10 @@ static void vorbis_cleanup(AVFormatContext *s, int idx)
         av_vorbis_parse_free(&priv->vp);
         for (i = 0; i < 3; i++)
             av_freep(&priv->packet[i]);
+
+        av_freep(&priv->header);
+        av_freep(&priv->comment);
+        av_freep(&priv->setup);
     }
 }
 
@@ -434,6 +444,9 @@ static int vorbis_packet(AVFormatContext *s, int idx)
     struct ogg_stream *os = ogg->streams + idx;
     struct oggvorbis_private *priv = os->private;
     int duration, flags = 0;
+    int skip_packet = 0;
+    int ret, new_extradata_size;
+    PutByteContext pb;
 
     if (!priv->vp)
         return AVERROR_INVALIDDATA;
@@ -496,10 +509,50 @@ static int vorbis_packet(AVFormatContext *s, int idx)
         if (duration < 0) {
             os->pflags |= AV_PKT_FLAG_CORRUPT;
             return 0;
-        } else if (flags & VORBIS_FLAG_COMMENT) {
-            vorbis_update_metadata(s, idx);
+        }
+
+        if (flags & VORBIS_FLAG_HEADER) {
+            ret = vorbis_parse_header(s, s->streams[idx], os->buf + os->pstart, os->psize);
+            if (ret < 0)
+                return ret;
+
+            ret = av_reallocp(&priv->header, os->psize);
+            if (ret < 0)
+                return ret;
+
+            memcpy(priv->header, os->buf + os->pstart, os->psize);
+            priv->header_size = os->psize;
+
+            skip_packet = 1;
+        }
+
+        if (flags & VORBIS_FLAG_COMMENT) {
+            ret = vorbis_update_metadata(s, idx);
+            if (ret < 0)
+                return ret;
+
+            ret = av_reallocp(&priv->comment, os->psize);
+            if (ret < 0)
+                return ret;
+
+            memcpy(priv->comment, os->buf + os->pstart, os->psize);
+            priv->comment_size = os->psize;
+
             flags = 0;
+            skip_packet = 1;
+        }
+
+        if (flags & VORBIS_FLAG_SETUP) {
+            ret = av_reallocp(&priv->setup, os->psize);
+            if (ret < 0)
+                return ret;
+
+            memcpy(priv->setup, os->buf + os->pstart, os->psize);
+            priv->setup_size = os->psize;
+
+            skip_packet = 1;
         }
+
         os->pduration = duration;
     }
 
@@ -521,7 +574,31 @@ static int vorbis_packet(AVFormatContext *s, int idx)
         priv->final_duration += os->pduration;
     }
 
-    return 0;
+    if (priv->header && priv->comment && priv->setup) {
+        new_extradata_size = priv->header_size + priv->comment_size + priv->setup_size + 6;
+
+        ret = av_reallocp(&os->new_extradata, new_extradata_size);
+        if (ret < 0)
+            return ret;
+
+        os->new_extradata_size = new_extradata_size;
+        bytestream2_init_writer(&pb, os->new_extradata, new_extradata_size);
+        bytestream2_put_be16(&pb, priv->header_size);
+        bytestream2_put_buffer(&pb, priv->header, priv->header_size);
+        bytestream2_put_be16(&pb, priv->comment_size);
+        bytestream2_put_buffer(&pb, priv->comment, priv->comment_size);
+        bytestream2_put_be16(&pb, priv->setup_size);
+        bytestream2_put_buffer(&pb, priv->setup, priv->setup_size);
+
+        av_freep(&priv->header);
+        priv->header_size = 0;
+        av_freep(&priv->comment);
+        priv->comment_size = 0;
+        av_freep(&priv->setup);
+        priv->comment_size = 0;
+    }
+
+    return skip_packet;
 }
 
 const struct ogg_codec ff_vorbis_codec = {
diff --git a/tests/ref/fate/ogg-vorbis-chained-meta.txt b/tests/ref/fate/ogg-vorbis-chained-meta.txt
index b7a97c90e2..1206f86c1f 100644
--- a/tests/ref/fate/ogg-vorbis-chained-meta.txt
+++ b/tests/ref/fate/ogg-vorbis-chained-meta.txt
@@ -6,10 +6,7 @@ Stream ID: 0, frame PTS: 128, metadata: N/A
 Stream ID: 0, packet PTS: 704, packet DTS: 704
 Stream ID: 0, frame PTS: 704, metadata: N/A
 Stream ID: 0, packet PTS: 0, packet DTS: 0
-Stream ID: 0, packet PTS: 0, packet DTS: 0
 Stream ID: 0, new metadata: encoder=Lavc61.19.100 libvorbis:title=Second Stream
-Stream ID: 0, packet PTS: 0, packet DTS: 0
-Stream ID: 0, packet PTS: 0, packet DTS: 0
 Stream ID: 0, frame PTS: 0, metadata: N/A
 Stream ID: 0, packet PTS: 128, packet DTS: 128
 Stream ID: 0, frame PTS: 128, metadata: N/A
-- 
2.39.5 (Apple Git-154)



More information about the ffmpeg-devel mailing list