Error trying to join FLV files with MEncoder

[sldvd]

I'm trying to join some FLV files using MEncoder (using a command I found online), and I got this error about the audio format being incompatible with -oac copy. Since I want the output file to be the same format as the input files, I don't see why it's saying the audio format is incompatible? I also don't know why it is saying the output file format will be AVI?

C:\Documents and Settings\username\My Documents>mencoder -oac copy -ovc copy -forceidx -o joined.flv part1.flv part2.flv
MEncoder Sherpya-SVN-r33216-4.2.5 (C) 2000-2011 MPlayer Team
162 audio & 365 video codecs

WARNING: OUTPUT FILE FORMAT IS _AVI_. See -of help.
success: format: 0  data: 0x0 - 0x758afbe
libavformat file format detected.
[flv @ 002782b0] Estimating duration from bitrate, this may be inaccurate
[lavf] stream 0: video (h264), -vid 0
[lavf] stream 1: audio (aac), -aid 0
VIDEO:  [H264]  854x478  0bpp  29.970 fps  1014.2 kbps (123.8 kbyte/s)
[V] filefmt:44  fourcc:0x34363248  size:854x478  fps:29.970  ftime:=0.0334
videocodec: framecopy (854x478 0bpp fourcc=34363248)
Audio format 0x4134504d is incompatible with '-oac copy', please try '-oac pcm'
instead or use '-fafmttag' to override it.

Exiting...

[dylz]

Here's an easier joiner https://www.videohelp.com/tools/Andys_FLV_Joiner if you need the CL then someone else will help.

[sldvd]

Thanks for pointing that out. Although I'm still curious if MEncoder can do it too, if anyone knows...

[Placio74]

Although I'm still curious if MEncoder can do it too, if anyone knows...

I think so - but I'm not sure what about A/V synchro (when source has a variable frame rate)...
- for FLV container (at output) you must to use libavformat: -of lavf
- for copying AAC audio you must set audio tag: -fafmttag 0x00ff

...I also don't know why it is saying the output file format will be AVI? ...

Without using libavformat, MEncoder can write only to AVI or MPG container and to raw audio or video.


BTW... from docs:

Unfortunately, as MEncoder was not designed from the beginning to support container formats other than AVI, your should really be paranoid about the resulting file. Please check to be sure that the audio/video synchronization is OK and that the file can be played correctly by players other than MPlayer.

[sldvd]

I think so - but I'm not sure what about A/V synchro (when source has a variable frame rate)...
- for FLV container (at output) you must to use libavformat: -of lavf
- for copying AAC audio you must set audio tag: -fafmttag 0x00ff

Thanks for that, although when I add the -of lavf and -fafmttag 0x00ff to my MEncoder command, I get this error after it finishes copying the first video file, so I guess the audio in the second video file doesn't match the audio in the first video file:

All files must have identical audio codec and format for -oac copy.

Exiting...

FFmpeg says the first and second video files both have audio "Audio: aac, 44100 Hz, stereo, s16, 99 kb/s", but I guess they are still different somehow.

I did try Andy's FLV Joiner to merge my video files, but VLC player automatically restarts the video when it hits the first join point. FFmpeg also failed to do a lossless copy of the joined video file (it gave an error about "non monotone timestamps" when it hit the first join point), so there seems to be something wrong with how Andy's FLV Joiner does joins.

Unfortunately, as MEncoder was not designed from the beginning to support container formats other than AVI, your should really be paranoid about the resulting file. Please check to be sure that the audio/video synchronization is OK and that the file can be played correctly by players other than MPlayer.

Ah, maybe that explains this... The last thing I tried was to use the MEncoder command with the -nosound option to join the video files. Then I used FFmpeg to mux the video from the MEncoder joined file with the audio from Andy's joined file, and it worked with no errors. But then when I tried to play the resulting video file, the audio was out of sync. I'm out of ideas now.

[Placio74]

And FLV files have same properties (frame rate, resolution, ...)?
Also possible to have variable frame rate, which may give a A/V desync (MEncoder does not support VFR).