How to merge FLV or MP4 (MPEG-4 AVC + AAC) files (or convert, then merge)

[cmdj1982]

Can anyone help me properly merge my mp4s? I've tried some "mp4 mergers" out there, but they all suck. All the generic video mergers don't work either. If anything has successfully merged my files, they all get more and more out of synch as the video progresses after each newly merged part starts playing.

I've been trying to make VirtualDub mp4 compatible and I've gotten to the point where I can open mp4s for editing through AVISynth Script, but I cannot append the segments like I want to addon the next files to the end of the first. If I must I suppose I can re-encode them to avi and merge them, but I'd really rather not. Any suggestions? I tried opening the mp4s in avidemux, but no dice. Unrecognizable format.

The mp4s are being recorded from a flash-embedded source and are saved as flvs are my HD, then I use FLVExtract to get them into h.264/aac mode and mux them together with Yamb to get the resulting mp4 specs (from GSpot):

Codec: avc1
Name: H.264/MPEG-4 AVC
Status: Codec Status Undetermined
kbps: 1138
fps: 29.971
Audio: mp4a1-MPEG-4 AAC LC
kbps: 47kb/s

These specs are universal for all my muxed mp4s, as well as the aspect ratio of 640x360. I've tried simply using Yamb to merge them, but the result is a full-size media file that pops out and plays all the video streams at once instead of sequentially. Very annoying and frustrating.


Fortunately I can play the files at this point on my WDTV player, which is the end-goal, but I really want them merged into one file for ease of file management and sharing.

Thanks a ton for any and all help! Again, my name problem with the merging is that the audio gets out of synch as the merged files progress (because of the way those generic programs merge files, it's not done very seamlessly). Just need one that will merge while keeping the audio in synch the whole time.

[cmdj1982]

Yay! I found a solution to my problem on another site. I'm just excited so I'm posting the solution if anyone else has this issue:

"You could try muxing it into .mkv container, and join it (with mkvmergeGUI), export the streams and then use YAMB to switch containers"

Final process for me:

Download media
Extract to h.264/aac with FLVExtract
Mux/combine streams to mp4 with Yamb
Merge/mux all desired mp4s together with MKVToolNix
Re-extract stream to h.264/aac with MKVExtract GUI2
Re-mux/combine streams to mp4 with Yamb

I now have one merged mp4 with seamless audio and video, and all without re-encoding a single frame throughout the entire process!

Originally Posted by cmdj1982

Final process for me:

Download media
Extract to h.264/aac with FLVExtract
Mux/combine streams to mp4 with Yamb
Merge/mux all desired mp4s together with MKVToolNix
Re-extract stream to h.264/aac with MKVExtract GUI2
Re-mux/combine streams to mp4 with Yamb

I would simplify things. Don't see any sense extracting audio/video tracks from FLV, than muxing them into MP4.

You can remux FLV into MKV directly. I use Replay Media Catcher 4 for that:




You can also try to use command line ffmpeg directly. Or you can try to remux FLV into MKV using freeware Avidemux.

[cmdj1982]

Originally Posted by Stream Recorder

I would simplify things. Don't see any sense extracting audio/video tracks from FLV, than muxing them into MP4.

The reason for this was to mux the mp4s into one large mkv file. No video merger would do it properly for me, but muxing them together into an mkv worked. Then in order to play the file on my WDTV (which won't read the muxed file), I have to re-extract into h.264/aac and re-mux into mp4 with Yamb.

This is all I've found that's worked so far. I'm certainly open to a much simpler process, though. I think using RMC4 will save me a little time though instead of having to use Yamb twice in the process. I didn't realize I could convert directly to mkv. Thanks for the tip!

Originally Posted by cmdj1982

I didn't realize I could convert directly to mkv.

It works really well for me even when FLV files use video codecs other than MPEG-4 AVC (h.264).

I use freeware tcpmp on my Windows Mobile cell phone. It doesn't play some FLV files, but after remuxing them into MKV I can play the files without any problem. No need to spend $40 onto CorePlayer

Initially I was using RMC to remux into MP4, but I had some problems with On VPx video codecs. MKV container seems to be better. No wonder it is supported by more and more hardware players.

I must admit, that I could play most of the videos online, but I prefer to increase the playback speed.

Sorry for off topic.