VLC conversion of .mp4 files working partially

[jalcaid001]

Hi,

Sometimes I convert a file and the resulting file doesn't play for the first ~5 secs, like if there was a sync problem. Doesn't happen always. And some files that were converted correctly with 3.0.8 are not when I convert them again with 3.0.16.

Is this known? Any solution?


H264 + MPEG AAC mp4a (from a Samsung phone video camera)
Use profile: H.264 + MP3 (MP4): Video Same as source, Codec MPEG 4 Audio (AAC), 128 kb/s, 2 channesl 48000 Hz

[Lotesdelere]

There are other reports about conversion issues:
https://forum.videolan.org/viewtopic.php?f=14&t=158673
https://forum.videolan.org/viewtopic.ph ... 89#p508489

Try with a nightly build:
https://nightlies.videolan.org

Or use a dedicated video tool such as AviDemux:
http://avidemux.sourceforge.net

[jalcaid001]

Nightly build didn't work

Anyway, I tried again with 3.0.8 and it works. But problem doesn't seem to be just the conversion. IT's the way VLC plays it.
I played the same converted videos with avidemux w/o problems.

[jalcaid001]

When I convert with VLC to x264 with default parameters, I get files about 1/2 size . What is the equivalent in Avidemux?

Is the quality option I see equivalent to Avidemux Quantizer? IS it like Constant Quantizer in Avidemux (https://www.avidemux.org/admWiki/doku.p ... rial:h.264)?

[Lotesdelere]

IMO it's all about the CRF value. I have explained it here:

https://forum.videolan.org/viewtopic.php?f=14&t=158610
https://forum.videolan.org/viewtopic.php?f=2&t=158117

[jalcaid001]

IMO it's all about the CRF value. I have explained it here:

https://forum.videolan.org/viewtopic.php?f=14&t=158610
https://forum.videolan.org/viewtopic.php?f=2&t=158117

I didn't see any CRF option on Tools -> Preferences -> Show settings: All -> Input/Codecs -> Video codecs -> x264 (similar entries to the image below)



Are you talking about 'video quality post processing level' ?

In anycase the quality factor may mean CRF (constant rate factor) or Cosntant Quantizier (per Avidemux options). Which one is VLC using?

[Lotesdelere]

As I said in the threads I've mentionned, in VLC the CRF setting is named Quality-based VBR in Tools -> Preferences -> Show settings: All -> Input/Codecs -> Video codecs -> x264.

[jalcaid001]

Oh... I realized what I was missing.. I had to do 'Show All' to see the option you were talking about.

I have been playing with it and perhaps I found I bug (or I'm missing something). LEt me explain:

Original file: 19Mb
I reset preferences on VLC, Quality-vased VBR = 23
I encode and I get a file of ~8k. About what I get with Avidemux
I change preferences to Quality-vased VBR = 22. I get 22MB (way too big !)
I change preferences again to Quality-vased VBR = 23. I get 19MB (way too big !)

al
So it looks some other parameter is being changed when I change 'Quality-vased VBR'. I went through all parameters on Input/Codecs -> Video codecs -> x264 and I didn't see a difference.