distortion on speex playback

[rach]

Summary of the bug:
this ​sample play with distortion, fine with libspeex (original report from ​doom9 forum)
Possible fix ​here (from librempeg) and confirmed playback better

[shenlebantongying]

I can confirm that this is happening with FFmpeg 7.0.1 found in a related project ​https://github.com/xiaoyifang/goldendict-ng/issues/1707#issuecomment-2251999373

Sample speex audios that previously works.

​https://github.com/user-attachments/files/16386866/dsl.zip

[shenlebantongying]

After this change (​https://git.ffmpeg.org/gitweb/ffmpeg.git/blobdiff/49726a922fd2b358feb7753488d415180da5121c..4a0e1cfc6f33d152e007849f6de7028d651de2af:/libavcodec/speexdec.c), these files are still wrong.

The test files above can be fixed by hardcoding frame_size to 640 (which I know isn't a proper fix):

diff --git a/libavcodec/speexdec.c b/libavcodec/speexdec.c
index b335e2fbe8..2531f62cf3 100644
--- a/libavcodec/speexdec.c
+++ b/libavcodec/speexdec.c
@@ -1426,6 +1426,7 @@ static int parse_speex_extradata(AVCodecContext *avctx,
         s->frame_size >     INT32_MAX >> (s->mode > 1))
         return AVERROR_INVALIDDATA;
     s->frame_size <<= (s->mode > 1);
+    s->frame_size = 640;
     s->vbr = bytestream_get_le32(&buf);
     s->frames_per_packet = bytestream_get_le32(&buf);
     if (s->frames_per_packet <= 0 ||

[shenlebantongying]

Someone sent a related patch which should fix this (i didn't test this claim.),

https://ffmpeg.org/pipermail/ffmpeg-devel/2025-March/341134.html

[James]

Should be fixed in c14b837dedade432a5f95981c3b1677099015376. Reopen if not.