Please help. version 2.6 file sizes much bigger than v.2.5 making mp4s?

[Fumz]

I make game videos and compress with h.264 codec. With version 2.5 of avidemux I used avsproxy to open the file, then "copy" I select mp4 AVC. I use the default constant rate factor; audio is AAC (faac) and the format is mp4. Things have worked great until Dxtory's latest update. For some reason avidemux won't open some Muxed files, so I got v.2.6 of avidemux.

However, file sizes are much bigger and I can't figure out how to get them smaller and maintain the same quality as the previous version? Video output is mpeg4 avc (h264). I use the same default constant rate factor, the same AAC (faac) for audio, and the MP4Muxer for the output. Last night a 2.6GB file only shrank to 1.2GB's? Normally this would have been ~ 500something using  version 2.5.

What am I doing wrong? Please help. Thank you.

[Jan Gruuthuse]

mark 1 minute in your video [A ][ B] the test RC and save.
RC20 with 720x576 produces video at 5198 Kbps size 40.0 MiB
RC25 with 720x576 produces video at 2194 Kbps size 18.3 MiB
Use MediaInfo to check parameters in your videos.
Check info of one of your old conversions (the best you have) and compare against the newly created. Eyeball the video itself if result is acceptable.

[Fumz]

Hi Jan Gruuthuse,

Thanks for the reply; although, I'm not sure I understand what you mean? I'm fairly new to all this... brand new.

What I can tell you is that when compressing my videos using avidemux 2.6's default constant rate factor, they're huge; they only compress to ~ half their original size. Just running a few sample videos through I can tell you that the bit rate is really high ( 9k+-15k) compared to avidemux v2.5, which does this at a bit rate of ~ 3-5k. I just don't know why the same setting is making videos so much bigger now?

The reason I'm asking is that for some reason after upgrading to the latest version of Dxtory (which is supposedly faster with DX9 games) a few of my muxes have strange issues. Using avidemux 2.5 the muxed videos compress, but the last minute or two gets cut off. If I try and run that muxed file through avidemux again I get an error. It happens about every 3rd video now, which is why I looked into 2.6. I just can't figure out which options to use to make files sizes smaller?

It was my understanding that using the default constant rate factor when compressing made better quality video than using constant bitrate? I can use constant bitrate if constant rate factor is no longer a viable option; is it?

**edit**

Just ran a small test using your tool. I compressed a 465MB 4 min muxed video using avidemux 2.6 into an mp4 using the default constant rate factor and the file size is now 227MB with a bitrate of 7,092 Kpbs.
Compressing that same 465MB file with v2.5 of avidemux, using the same default constant rate factor, creating the same mp4 the file size is 88MB with a bitrate of 2,665 Kbps.

[Jan Gruuthuse]

In configure move slider from 20 to 25, or even greater, (constant rate factor)  or somewhere in between. Operation is most likely changed due to changed settings or encoder upgrade.
Lower numbers indicates greater quality = bigger file size
Higher numbers indicates lower quality = smaller file size

[mean]

If the CRF is the same, something else has changed

[Jan Gruuthuse]

When starting in MPEG-4 AVC x264 Constant Rate Factor is in:
2.5.6 = 26
2.6.0 = 20

[mean]

That would explain the difference in size

[Fumz]

Thanks guys, I'll give it a shot as soon as I get downstairs!

***edit***

That seems to have been it. Thank you.

[Jan Gruuthuse]

Your welcome, enjoy avidemux!