[FFmpeg-devel] [PATCH 2/2] Add experimental demuxing support for FLAC in ISO BMFF (MP4).

[Matthew Gregan]

Based on the draft spec at https://git.xiph.org/?p=flac.git;a=blob;f=doc/isoflac.txt

Signed-off-by: Matthew Gregan <kinetik at flim.org>
---
 libavformat/mov.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 357d800..fc36b0e 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -4684,6 +4684,46 @@ static int mov_read_saiz(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     return 0;
 }
 
+static int mov_read_dfla(MOVContext *c, AVIOContext *pb, MOVAtom atom)
+{
+    const size_t FLAC_STREAMINFO_SIZE = 34;
+    AVStream *st;
+    uint8_t type;
+    size_t size;
+
+    if (c->fc->nb_streams < 1)
+        return 0;
+    st = c->fc->streams[c->fc->nb_streams-1];
+
+    if ((uint64_t)atom.size > (1<<30) || atom.size < 42)
+        return AVERROR_INVALIDDATA;
+
+    /* Check FlacSpecificBox version. */
+    if (avio_r8(pb) != 0)
+        return AVERROR_INVALIDDATA;
+
+    avio_rb24(pb); /* Flags */
+
+    type = avio_r8(pb);
+    /* TODO: Read other METADATA_BLOCK_TYPEs if the decoder wants them. */
+    if (!(type & 0x80)) {
+      av_log(c->fc, AV_LOG_WARNING, "ignoring non-STREAMINFO FLACMetadataBlocks\n");
+    }
+    type = type & 0x7f;
+    size = avio_rb24(pb);
+
+    /* The first METADATA_BLOCK_TYPE must be STREAMINFO. */
+    if (type != 0 || size != FLAC_STREAMINFO_SIZE)
+        return AVERROR_INVALIDDATA;
+
+    if (ff_alloc_extradata(st->codecpar, size))
+        return AVERROR(ENOMEM);
+
+    avio_read(pb, st->codecpar->extradata, size);
+
+    return 0;
+}
+
 static int cenc_filter(MOVContext *c, MOVStreamContext *sc, uint8_t *input, int size)
 {
     uint32_t encrypted_bytes;
@@ -4858,6 +4898,7 @@ static const MOVParseTableEntry mov_default_parse_table[] = {
 { MKTAG('f','r','m','a'), mov_read_frma },
 { MKTAG('s','e','n','c'), mov_read_senc },
 { MKTAG('s','a','i','z'), mov_read_saiz },
+{ MKTAG('d','f','L','a'), mov_read_dfla },
 { 0, NULL }
 };
 
-- 
2.10.1