avformat/vorbiscomment: Switch to AVIOContext from bytestream API

Up until now ff_vorbiscomment_write() used the bytestream API to write
VorbisComments. Therefore the caller had to provide a sufficiently large
buffer to write the output.

Yet two of the three callers (namely the FLAC and the Matroska muxer)
actually want the output to be written via an AVIOContext; therefore
they allocated buffers of the right size just for this purpose (i.e.
they get freed immediately afterwards). Only the Ogg muxer actually
wants a buffer. But given that it is easy to wrap a buffer into an
AVIOContext this commit changes ff_vorbiscomment_write() to use an
AVIOContext for its output.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

1 files changed, 4 insertions, 14 deletions

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 80ff341a90..c07aa4f7e4 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -624,7 +624,7 @@ static int put_flac_codecpriv(AVFormatContext *s, AVIOContext *pb,
         const char *vendor = (s->flags & AVFMT_FLAG_BITEXACT) ?
                              "Lavf" : LIBAVFORMAT_IDENT;
         AVDictionary *dict = NULL;
-        uint8_t buf[32], *data, *p;
+        uint8_t buf[32];
         int64_t len;
 
         snprintf(buf, sizeof(buf), "0x%"PRIx64, par->channel_layout);
@@ -633,21 +633,11 @@ static int put_flac_codecpriv(AVFormatContext *s, AVIOContext *pb,
         len = ff_vorbiscomment_length(dict, vendor, NULL, 0);
         av_assert1(len < (1 << 24) - 4);
 
-        data = av_malloc(len + 4);
-        if (!data) {
-            av_dict_free(&dict);
-            return AVERROR(ENOMEM);
-        }
-
-        data[0] = 0x84;
-        AV_WB24(data + 1, len);
-
-        p = data + 4;
-        ff_vorbiscomment_write(&p, dict, vendor, NULL, 0);
+        avio_w8(pb, 0x84);
+        avio_wb24(pb, len);
 
-        avio_write(pb, data, len + 4);
+        ff_vorbiscomment_write(pb, dict, vendor, NULL, 0);
 
-        av_freep(&data);
         av_dict_free(&dict);
     }