When specifying -acodec nellymoser ffmpeg does not recognize stream specifier

[haraldbre]

Summary of the bug:
Concatenating nellymoser encoded audio streams to .mp3 usually works when setting input codecs via "-acodex nellymoser". In some instances however it fails:

Stream specifier ':3' in filtergraph description [0:0][0:2][0:3] concat=n=3:v=0:a=1 matches no streams.

When setting input codecs individually via "-codec:a:0 nellymoser -codec:a:1 nellymoser .." there is no problem.

How to reproduce:
ffmpeg -acodec nellymoser -i ​http://www.hwjyw.com/textbook/dzjc/zh/cd12/main11/content/CzdB_001.swf -filter_complex "[0:0][0:2][0:3] concat=n=3:v=0:a=1" temp.mp3
==>

[swf @ 0x5620fa937240] SWF compressed file detected
Input #0, swf, from 'http://www.hwjyw.com/textbook/dzjc/zh/cd12/main11/content/CzdB_001.swf':
  Duration: 00:00:02.74, bitrate: 3137 kb/s
    Stream #0:0: Audio: nellymoser, 44100 Hz, mono, flt
    Stream #0:1: Video: rawvideo (ARGB / 0x42475241), argb, 149x119, 25 fps, 25 tbr, 25 tbn
    Stream #0:2: Audio: nellymoser, 44100 Hz, mono, flt
Stream specifier ':3' in filtergraph description [0:0][0:2][0:3] concat=n=3:v=0:a=1 matches no streams.

ffmpeg -codec:a:0 nellymoser -codec:a:1 nellymoser -codec:a:2 nellymoser -i ​http://www.hwjyw.com/textbook/dzjc/zh/cd12/main11/content/CzdB_001.swf -filter_complex "[0:0][0:2][0:3] concat=n=3:v=0:a=1" temp.mp3
==>

[swf @ 0x556d10114240] SWF compressed file detected
[swf @ 0x556d10114240] Could not find codec parameters for stream 0 (Audio: none, 44100 Hz, mono): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' options
[swf @ 0x556d10114240] Could not find codec parameters for stream 2 (Audio: none, 44100 Hz, mono): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' options
[swf @ 0x556d10114240] Could not find codec parameters for stream 3 (Audio: none, 44100 Hz, mono): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, swf, from 'http://www.hwjyw.com/textbook/dzjc/zh/cd12/main11/content/CzdB_001.swf':
  Duration: 00:00:04.31, bitrate: 1996 kb/s
    Stream #0:0: Audio: nellymoser, 44100 Hz, mono
    Stream #0:1: Video: rawvideo (ARGB / 0x42475241), argb, 149x119, 25 fps, 25 tbr, 25 tbn
    Stream #0:2: Audio: nellymoser, 44100 Hz, mono
    Stream #0:3: Audio: nellymoser, 44100 Hz, mono
Stream mapping:
  Stream #0:0 (nellymoser) -> concat:in0:a0
  Stream #0:2 (nellymoser) -> concat:in1:a0
  Stream #0:3 (nellymoser) -> concat:in2:a0
  concat -> Stream #0:0 (libmp3lame)

[Carl Eugen Hoyos]

Needs -analyzeduration 75M.
Much more important: Do you know where this file comes from?

For future tickets: Please test current FFmpeg git head, the only version supported here and always provide the command line you tested together with the complete, uncut console output.

[Balling]

Actually it is just disallowed in ffmpeg ​https://patchwork.ffmpeg.org/project/ffmpeg/patch/CAB0OVGrZmYv41bcdXLzk-g2S+24DOPqW2FktKggWaPv79W4b1Q@mail.gmail.com/

[Carl Eugen Hoyos]

There may be an issue in ffmpeg with how acodec works for not-yet-detected streams but for Nellymoser in swf, I fixed the issue in 9f8c81efc51755a8ff02c1cf02a7585d998e1380