Help wanted: Speex (commonly used in mdx) is currently broken in FFmpeg7.0

[shenlebantongying]

• https://trac.ffmpeg.org/ticket/11054
• https://trac.ffmpeg.org/ticket/11078

We need to delay Qt6.8 updates until these problems fixed. (Hopefully, the Qt6.7 doesn't bump major FFmpeg version yet.)

Help wanted to fix the bug in FFmpeg. (One reports says only a single line of change is needed.)

Furthermore, nobody else appears to use/care about this format anymore. FFmpeg could break silently again in future. Maybe we should implement/copy the speex decoder code to our source tree, as libspeex doesn't appear to be changing anymore (but other parts of FFmpeg keeps changing).

https://github.com/videolan/vlc/blob/master/modules/codec/speex.c

---

speex_mini.zip

Minimum dict to do test with a single entry “A” and 2 speex audios.

ffplay -> has exactly the same issue as GD

vlc -> no issue

[shenlebantongying]

Workarounds:

• uses VLC's no gui command line to play audio vlc --intf dummy --play-and-exit or cvlc
• On linux, force QT_MEDIA_BACKEND=gstreamer and ensure both the qt6's gstreamer backend installed and GStreamer codecs packages are installed (no idea which one, but some distros names them good/bad/ugly....)

[powerboat9]

Would https://fate.ffmpeg.org/ be useful?

[shenlebantongying]

There is no need to waste time on those things. They already exists in FFmpeg.

The task that needs to be performed is pretty much verify the 3 commits since April in the repo below, and put together a patch (with credit to the repo's author) and send it to FFmpeg's patch tracker.

https://github.com/librempeg/librempeg/commits/master/libavcodec/speexdec.c

[shenlebantongying]

The "Invalid data found when processing input" like #1707 comes from FFmpeg

Simply applying these changes to the tip of FFmpeg's code doesn't work https://github.com/librempeg/librempeg/commits/master/libavcodec/speexdec.c

speexdec a.spx a.wav outputs valid audio file using the sample that I attached before.

---

Not sure if I compiled FFmpeg wrong. I only use 3 options.

./configure \
--disable-everything \
--enable-protocol=file \
--enable-libspeex

[shenlebantongying]

Actually, I compiled the FFmpeg wrong.

./configure \
--enable-libspeex \
--enable-decoder=speex

make -j 8

./ffplay ~/Desktop/dsl/a.spx -loglevel 48 -autoexit

This patch for FFmpeg will fix the issue.

ffmpeg7-fix-speex.patch .

Now comes the real challenge. How to send this to FFmpeg's mailing list 😅😅😅?

Edit: https://ffmpeg.org//pipermail/ffmpeg-devel/2024-November/335743.html

Edit2: The author of speexdec.c quitted FFmpeg project btw, as according to

• https://codecs.multimedia.cx/2023/03/ffhistory-the-most-annoying-format/
• https://codecs.multimedia.cx/2023/01/ffhistory-paul-b-mahol/
• https://codecs.multimedia.cx/2023/12/another-fun-ffork/

Edit3: Code copied from a GPLv2 fork, cannot be merged to FFmpeg.

[xiaoyifang]

https://github.com/FFmpeg/FFmpeg/blob/master/CONTRIBUTING.md

[atauzki]

external player code seems have bug and just play a part of the sound sometimes. so I have to recompile qtmultimedia with ffmpeg 6.1 just follow qt's build param and it's the compiled binary:
https://cloud.freemdict.com/index.php/s/Y2DMdNRkRKooD2g