[FFmpeg-cvslog] vorbisdec: Accept 0 amplitude_bits
Luca Barbato
git at videolan.org
Sun Mar 3 12:11:01 CET 2013
ffmpeg | branch: release/1.1 | Luca Barbato <lu_zero at gentoo.org> | Sun Feb 24 16:56:15 2013 +0100| [c6c4dc69354f72376708ded9bb56af4a58082f1d] | committer: Reinhard Tartler
vorbisdec: Accept 0 amplitude_bits
The specification does not prevent an encoder to write the amplitude 0
as 0 amplitude_bits.
Our get_bits() implementation might not support a zero sized read
properly, thus the additional branch.
(cherry picked from commit 23bd9ef4b209c789d5473d75f89a2e411d343d80)
Conflicts:
libavcodec/vorbisdec.c
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c6c4dc69354f72376708ded9bb56af4a58082f1d
---
libavcodec/vorbisdec.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/libavcodec/vorbisdec.c b/libavcodec/vorbisdec.c
index cfa89be..884cd5b 100644
--- a/libavcodec/vorbisdec.c
+++ b/libavcodec/vorbisdec.c
@@ -603,13 +603,6 @@ static int vorbis_parse_setup_hdr_floors(vorbis_context *vc)
return AVERROR_INVALIDDATA;
}
floor_setup->data.t0.amplitude_bits = get_bits(gb, 6);
- /* zero would result in a div by zero later *
- * 2^0 - 1 == 0 */
- if (floor_setup->data.t0.amplitude_bits == 0) {
- av_log(vc->avccontext, AV_LOG_ERROR,
- "Floor 0 amplitude bits is 0.\n");
- return AVERROR_INVALIDDATA;
- }
floor_setup->data.t0.amplitude_offset = get_bits(gb, 8);
floor_setup->data.t0.num_books = get_bits(gb, 4) + 1;
@@ -1063,6 +1056,9 @@ static int vorbis_floor0_decode(vorbis_context *vc,
unsigned amplitude, book_idx;
unsigned blockflag = vc->modes[vc->mode_number].blockflag;
+ if (!vf->amplitude_bits)
+ return 1;
+
amplitude = get_bits(&vc->gb, vf->amplitude_bits);
if (amplitude > 0) {
float last = 0;
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