[FFmpeg-user] Glitch between audio concat files

Vicente M v1c3nt3 at ymail.com
Tue Sep 1 17:34:42 CEST 2015


I'm involved in a developing of a linux application that records raw audio and later encodes to OGG vorbis. The audio is stored in 1 min duration OGG files for later concat the desired minutes in other OGG file. My problem is that the concat result audio presents a glitch in some junctions.

I try to encode the 1-minute raw files and later concatenate, all with ffmpeg directly and the result is the same. A example:

ffmpeg -f s16le -ac 2 -i 1.raw -c:a libvorbis -ac 1 -b:a 64k 1.ogg

ffmpeg -f s16le -ac 2 -i 2.raw -c:a libvorbis -ac 1 -b:a 64k 2.ogg

ffmpeg -f concat -i myfilelist.txt -c:a copy cat.ogg

where myfilelist.txt contains:

file '1.ogg'
file '2.ogg'

The raw audio is recorded as signed 16 bit little endian stereo at 44100hz and is encoded to OGG vorbis (libvorbis) mono 64kbits/s. The original raw files do not present any glitch and if i simply cat the raw files and them encode, there is no mistake. But nevertheless the cat.ogg file presents a glitch in the middle of the file.

Is this a normal lossy behavior for the codec? Am I doing something wrong? I appreciate any comment.

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