From 23bd9ef4b209c789d5473d75f89a2e411d343d80 Mon Sep 17 00:00:00 2001
From: Luca Barbato <lu_zero@gentoo.org>
Date: Sun, 24 Feb 2013 16:56:15 +0100
Subject: [PATCH] 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.
---
libavcodec/vorbisdec.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/libavcodec/vorbisdec.c b/libavcodec/vorbisdec.c
index 7575ee41819..0513d972da8 100644
--- a/libavcodec/vorbisdec.c
+++ b/libavcodec/vorbisdec.c
@@ -602,13 +602,6 @@ 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) {
- 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;
@@ -1059,6 +1052,9 @@ 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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