Joining x264 mp4 files issue

[dreamweaver888]

Greetings all, I'm attempting to join a multi-segment YouTube video. The segments are encoded x264 mp4 files, and I was able to successfully join most of them, 1-by-1, using Avidemux, without re-encoding. However, one of the middle segments, when joined, results in playability issues in VLC media player: the video freezes at the join, while audio continues playing. Strangely, there is no issue when playing in Quicktime, but it would be great if the file could be played in VLC due to its greater modes (particularly zooming in as the video is letterboxed with static at the edges). All joins were done using Avidemux except where noted.

1. Diagnostic measures taken: joined the segments without the problematic middle one--no playability issues. Therefore isolating this particular problem section. Downloaded the video again, same join issues.

2. Attempted different program: tried joining using YAMB, and same issue.

3. Attempted conversion: extracted video and audio tracks in raw format using YAMB, and re-muxed as mp4; joined again, same issue.

4. Attempted conversion: tried re-encoding the problem segment using Any Video Converter as an XVID; then re-encoded as x264, and attempted join, same issue.

5. Attempted conversion: re-downloaded segment as smaller FLV file, converted and upsized to x264 using Any Video Converter, attempted join, same issue.

6. Attempted re-encode: re-encoded multiple segments from x264 to XVID using Avidemux, and joined; some quality loss; plays fine in VLC, but choppy in QuickTime.

Any suggestions on how to solve this issue? I was hoping to avoid extensive re-encoding due to the quality loss. Looking at the file info on YAMB, the problematic segment does not seem to be different from the others, but whether there is some keyframe issue, or some other problem, that makes joined files lose video on VLC playback, is unclear to me, as is what should be the right course of action.

Thanks in advance for any suggestions for this novice! The programs used were selected following searches of this forum for suggestions to past similar cases.

[poisondeathray]

-you can try using mkvmerge to join/append, then re-wrap back into mp4 (or just leave it as mkv)

-you can try avidemux 2.6 beta builds, they handles h.264 better
http://avidemux.razorbyte.com.au/

-if bad join is from IDR frame not on frame 0, you can re-encode that segment with a qpfile specifing frame 0 as IDR

-if you're going to re-encode the whole thing, you might as well specify the joins with avisynth, but use x264 instead of xvid for better quality at a given bitrate

-you can try joining with videoredo 4 beta, or solveigmm, (both not free) but you can use the trial version

[budwzr]

I recently tried the new H.264 cutter/splitter/joiner from SolveigMM, to do the exact same thing, what a coincidence, and it works flawlessly.

[dreamweaver888]

Thanks to both of you for the suggestions, they provide good directions to try which I may attempt. While I was waiting for replies, I already re-encoded the whole thing using Avidemux and MPEG-4 ASP (avcodec) with AAC audio as a new .mp4 which plays well in both QT and VLC, with slight quality tradeoff, but I also used video filters to eliminate the static edges.

Thanks again for the suggestions, this forum is a great site for info!