encode and merge two G729 files to opus

[Asmaa]

Summary of the bug:
I am trying to encode and merge raw G729 Files into opus file

% ffmpeg -f g729 -i input1 -f g729 -i input2  -filter_complex  amerge  -acodec libopus -ab 13000 -ac 1  -y  -threads 1 output

ffmpeg version 4.2
built on ...

ffmpeg.exe output is :
[libopus @ 0626ca40] Queue input is backward in time.
and one second cut and distorted file.

* I solved the issue on a c++ code by:
1-decoding inputs frames
2-add them to filter graph
3-encode the output of the filter graph

filter graph built from :
-two "abuffer" filters for inputs
-one "amerge" filter
-"aformat" filter (to force output format to be the same as the input format)
-"sink" filter for the output

[Carl Eugen Hoyos]

Please test current FFmpeg git head and provide the command line you tested together with the complete, uncut console output to make this a valid ticket.

[Asmaa]

ffmpeg -f g729 -i "010665320552019103112553726.wa1" -f g729 -i "010665320552019103112553726.wa2" -filter_complex amerge -acodec libopus -ab 13000 -ac 1 -y -threads 1 "test255.opus"

ffmpeg version 4.2 Copyright (c) 2000-2019 the FFmpeg developers

built with gcc 9.1.1 (GCC) 20190807
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
libavutil 56. 31.100 / 56. 31.100
libavcodec 58. 54.100 / 58. 54.100
libavformat 58. 29.100 / 58. 29.100
libavdevice 58. 8.100 / 58. 8.100
libavfilter 7. 57.100 / 7. 57.100
libswscale 5. 5.100 / 5. 5.100
libswresample 3. 5.100 / 3. 5.100
libpostproc 55. 5.100 / 55. 5.100

[g729 @ 06385ec0] Estimating duration from bitrate, this may be inaccurate
Guessed Channel Layout for Input Stream #0.0 : mono
Input #0, g729, from '010665320552019103112553726.wa1':

Duration: 00:01:39.82, start: 0.000000, bitrate: 8 kb/s

Stream #0:0: Audio: g729, 8000 Hz, mono, s16p

[g729 @ 063914c0] Estimating duration from bitrate, this may be inaccurate
Guessed Channel Layout for Input Stream #1.0 : mono
Input #1, g729, from '010665320552019103112553726.wa2':

Duration: 00:01:39.82, start: 0.000000, bitrate: 8 kb/s

Stream #1:0: Audio: g729, 8000 Hz, mono, s16p

Stream mapping:

Stream #0:0 (g729) -> amerge:in0
Stream #1:0 (g729) -> amerge:in1
amerge -> Stream #0:0 (libopus)

Press [q] to stop, ? for help
[Parsed_amerge_0 @ 063e1340] No channel layout for input 1
[Parsed_amerge_0 @ 063e1340] Input channel layouts overlap: output layout will be determined by the number of distinct input channels
Output #0, opus, to 'test255.opus':

Metadata:

encoder : Lavf58.29.100
Stream #0:0: Audio: opus (libopus), 8000 Hz, mono, s16, 13 kb/s (default)
Metadata:

encoder : Lavc58.54.100 libopus

[libopus @ 0639c380] Queue input is backward in time

Last message repeated 353 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.243x

Last message repeated 377 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.216x

Last message repeated 366 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.205x

Last message repeated 362 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.199x

Last message repeated 386 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.198x

Last message repeated 380 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.197x

Last message repeated 376 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.195x

Last message repeated 383 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.195x

Last message repeated 381 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.195x

Last message repeated 391 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.195x

Last message repeated 351 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.192x

Last message repeated 330 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.19x

Last message repeated 395 times

[libopus @ 0639c380] Queue input is backward in time/s speed=0.191x

Last message repeated 145 times

size= 153kB time=00:00:01.28 bitrate= 978.2kbits/s speed=0.191x
video:0kB audio:147kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 3.755125%

[Carl Eugen Hoyos]

Is the issue reproducible with current FFmpeg git head?

[Asmaa]

Replying to cehoyos:

Is the issue reproducible with current FFmpeg git head?

yes , it is with the latest ffmpeg released build.

[Carl Eugen Hoyos]

Please reopen this ticket if the issue is reproducible with current FFmpeg git head, there is no release support on this bug tracker.