Some questions about Levels

[pihug12]

Hello !

I'm a beginner in H264 settings. I read somewhere that the PS3, the Popcorn Hour A-100 and the Western Digital TV cannot read H264 files with a level superior to @L4.1. Which parameters must I check when I encode my files to read them on these devices ?

I think it's --bframes and --ref but I'm not completely sure. (http://mewiki.project357.com/wiki/X264_Settings)
What value must I set ?

MediaInfo can retrieve the number of BFrames but not the number of "ref". Is there a way to know this number on an already encoded file ?

Thank you !
pihug12 :cool:

[wyti]

AVInaptic can give you this information (and he show the profile compliancy too, it's easier in that way.)

[pihug12]

I made a mistake in my first post. MediaInfo shows the number of "ref frames" (not BFrames) like AVInaptic.
But why a file with 12 ref frames is High@L4.0 and another with 5 ref frames is High@L5.0 ?
Is there a link between BFrames and level or only "ref frames" count ?

pihug12 :cool:

[Dark Shikari]

I made a mistake in my first post. MediaInfo shows the number of "ref" (not BFrames) like AVInaptic.
But why a file with 12 ref frames is High@L4.0 and another with 5 ref frames is High@L5.0 ?
Is there a link between BFrames and level or only "ref frames" count ?The limit is DPB size. Lower resolution means you can have more reference frames at the same level.

[pihug12]

If adhering to Level 4.1 specs, the maximum ref for full height 720p and 1080p video are 9 and 4 respectively. But if the video's height is not the full 720 or 1080 pixels, a higher ref can be used. The formula for calculating maximum ref is as follows, the value should be rounded down:

maximum ref = 12288 * 1024 / ( width * height * 1.5)

Source : http://mewiki.project357.com/wiki/X264_Settings#ref
OK I get it.
So only reference frames count for the level.

Thank you for all your answers !
pihug12 :cool:

[pihug12]

I made a small tool to calculate the maximum reference frames : http://localhostr.com/files/266b25/MaxRef.bat
(right click => save as... if it doesn't work)
@echo off
set /p Largeur=Entrez la largeur de la video en pixels ici :
set /p Hauteur=Entrez la hauteur de la video en pixels ici :
set /a MaxRef=(12288*1024)/(%Largeur%*%Hauteur%*3/2)
echo La valeur maximale du nombre d'images de reference doit etre de %MaxRef% pour eviter un niveau superieur a 4.1.
pause

I know, it's written in French and it's useless.
pihug12 :cool:

[Sagekilla]

Or you can just create a bat file with the following contents (identical to above):


@echo off
set /p width=Enter width
set /p height=Enter height
set /a MaxRef=(12288*1024)/(%width%*%height%*3/2)
echo The maximum number of reference frames for Level 4.1 is %MaxRef%
pause