Why can't Virtualdub Smart render two x264 clips?

[seanmcnally]

Trying to join two clips that are h.264 with no luck. As a test, I rendered them both using Virtualdub's x264 8-bit video encoder, and the LAME MP3 audio encoder, then tried to take those clips and join them together. Since they were both rendered using Vdub's own codec, I figured there wouldn't be an issue, but I'm getting an error when I try to stream copy:

Direct stream copy cannot be used with this video stream. You may want to select a different Input Driver.

And an error when I try full processing, smart render:

Cannot initialize smart rendering: The selected video codec is able to compress the source video, but cannot match the same compressed format.

Is this just a limitation of the x264 codec? Of course, my eventual use case would be to try and join two clips that weren't re-encoded by Vdub, but this experiment seems to suggest it isn't possible at all. Why is this?

[jagabo]

I believe the smart rendering only works with AVI files. And you generally shouldn't use x264 in AVI. And you may need to force the AVI File reader when you open the video.

[seanmcnally]

As in, .avi source and output files? Because .mp4 sources to .avi outputs didn't work, maybe I could try re-wrapping before my next attempt.

And you generally shouldn't use x264 in AVI

Why is this?

And you may need to force the AVI File reader when you open the video

And how do I do this?

[abolibibelot]

Some years ago I struggled to find a method that would losslessly join three or four MP4 / H.264 videos with no synchronization issue. The only one that worked flawlessly was ffmpeg with a temporary TS remuxing.

ffmpeg -i "input1.mp4" -c copy -bsf h264_mp4toannexb "temp1.ts"
ffmpeg -i "input2.mp4" -c copy -bsf h264_mp4toannexb "temp2.ts"
ffmpeg -i "input3.mp4" -c copy -bsf h264_mp4toannexb "temp3.ts"
ffmpeg -i "concat:temp1.ts|temp2.ts|temp3.ts" -c copy -absf aac_adtstoasc "output.mp4"

Disclaimer : I merely copied the content of the .bat file I used back then, with an older version of ffmpeg, I'm not sure what the "-bsf h264_mp4toannexb" and "-absf aac_adtstoasc" options were for, or if they were actually necessary, or if they still exist with recent versions. Someone may chime in to elaborate on this.

[jagabo]

As in, .avi source and output files? Because .mp4 sources to .avi outputs didn't work, maybe I could try re-wrapping before my next attempt.

The source has to be AVI.

And you generally shouldn't use x264 in AVI

Why is this?

The AVI container was designed before codecs used out-of-order encoding/decoding. And Microsoft's VFW library (which many programs use to read/play AVI) doesn't handle out-of-order frames. So one has to use tricks to use such codecs in AVI -- usually called "Virtualdub Hack" or "Packed Bitstream".

And you may need to force the AVI File reader when you open the video

And how do I do this?

At the Open Video File dialog use the Files Of Type pulldown to select Audio/Video Interleave (*.AVI, *.DIVX).