I have these flv files that exported from Adobe Connect and I want to extract their audio with ffmpeg. ffmpeg does not recognize the audio on some of them. This log is from one file that has issues:
>ffmpeg.exe -i r7anupl75gl_0_1965937.flv test1.mp3
ffmpeg version N-76123-g002b049 Copyright (c) 2000-2015 the FFmpeg
built with gcc 5.2.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads
libavutil 55. 4.100 / 55. 4.100
libavcodec 57. 7.100 / 57. 7.100
libavformat 57. 8.102 / 57. 8.102
libavdevice 57. 0.100 / 57. 0.100
libavfilter 6. 11.100 / 6. 11.100
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.100 / 2. 0.100
libpostproc 54. 0.100 / 54. 0.100
[flv @ 0000000000522140] Could not find codec parameters for stream 1
(Audio: none, 0 channels): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize'
options
Input #0, flv, from 'r7anupl75gl_0_1965937.flv':
Metadata:
lasttimestamp : 5026
lastkeyframetimestamp: 5022
audiodelay : 0
canSeekToEnd : false
creationdate : unknown
metadatacreator : Manitu Group FLV MetaData Injector 2
videosize : 251586025
audiosize : 55776880
datasize : 516
Duration: 01:23:47.75, start: 0.000000, bitrate: 489 kb/s
Stream #0:0: Video: vp6f, yuv420p, 1184x704, 1k tbr, 1k tbn, 1k tbc
Stream #0:1: Audio: none, 0 channels
Output #0, mp3, to 'test1.mp3':
Output file #0 does not contain any stream
Note: audio codec is Nellymoser Asao and this command works successfully for some files.
Consider increasing the value for the 'analyzeduration' and 'probesize'
The problem is in first 10-15 min the flv file doesn't actually have any audio. By increasing probesize and analyzeduration it looks further in the file to find audio and detect it.
In my scenario I have to set analyzeduration bigger than 5000000 (5 seconds).