What is format profile?

[bho]

Hey guys, I am a newbie. I have always wondered about what is the x265 or x264 format profile. You know like Main 10@L4@Main or High@5.1 or something? I just wanted to know why do we use it. Will the video quality be better if use higher profile?

[ndjamena]

https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Profiles
https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Levels

Main is the old, high is the new. Levels are about the capabilities of the target decoder (memory/ops). Obviously the new is better than the old and better hardware leads to better compression.

[bho]

So it has no relation with the quality of the video???

[Zee530]

10-bit encoding >> 8-bit encoding
X265 >> x264

[ndjamena]

Better compression = better quality if you use leave the bitrate static.

Quality is something you choose, any level/profile can give you near lossless quality, but the ones with better compression will give it to you at a lower bitrate.

[theewizard]

To say it another way
The New can give you the same quality of the old, in a smaller file size using the same bit rate
Bit rate= quality
Amount of compression "of that bit rate", equal file size

[bho]

I still am confused. So if I encode the same source with same settings except one is High Profile and the other in Main profile, both will have the same quality but the High Profile one will have a smaller size? Then what will happen if I encode in Controlled Bitrate Mode? Will the high profile have better quality or the Main profile or both will then be the same???

[jagabo]

I still am confused. So if I encode the same source with same settings except one is High Profile and the other in Main profile, both will have the same quality but the High Profile one will have a smaller size? Then what will happen if I encode in Controlled Bitrate Mode? Will the high profile have better quality or the Main profile or both will then be the same???

If you shoot for the same quality the High profile video will be smaller. If you encode at the same size (same bitrate) the High Profile version will have better quality. But if you have a player that only supports Main profile the High profile video may not play properly, or at all.

Note that the Profile@Level flag in the header of many files may not be accurate. Any program can write anything there. It doesn't necessarily mean the video conforms to that Profile@Level.

[bho]

If you shoot for the same quality the High profile video will be smaller. If you encode at the same size (same bitrate) the High Profile version will have better quality. But if you have a player that only supports Main profile the High profile video may not play properly, or at all.

Note that the Profile@Level flag in the header of many files may not be accurate. Any program can write anything there. It doesn't necessarily mean the video conforms to that Profile@Level.

Thanks.

[theewizard]

Jajabo and I seem to have a different opinion of what the terms bit rate means
I will defer to him
But to me bit rate is just that , the number of bits per pixel or frame, it's the rate of data flow
The more "bits" in a frame of video, the higher quality of the image
264 and 265 have different compression algorithms
Meaning 265 can have the same bit rate flow as 264 or some other codec, but store the completed file in a smaller file size

CBR is Constant bit rate aka FIXED bit rate , not controlled..everything is controlled wether uses FIXED constant or variable bit rate it is controlled by the settings used in the codec,
Basically cbr means the same amount of data per frame , the data flow rate does not change
Variable bit rate means the amount of data per frame changes, writhe amount of motion or image difference per frame, variable offers more compression smaller file size
I do not use it, my experience has been, if I use it , sequences frames containing lots of dark area always end up mottled looking , not smooth not black, it's distracting
But that's me and my visual preferences, I find cbr gives me the best conversions when recoding

[Cornucopia]

Level & profile refer to which FEATURES of the encoding format family should be supported by the CAPABILITIES of the decoder.

So, because High has more features available to it than Main, and L5.1 has more than L4.0, AS LONG AS THE DECODER SUPPORTS IT, you can take better advantage of those features' quality/bitrate "shortcuts" in the encoding, thus giving you better quality at a given bitrate (or conversely lower bitrate at the same quality, or a partial mixture of the two). Since most decoders which support a certain "max" set of levels & profiles also support those LOWER than that "max", you can pick & choose within those levels & profiles which features you want to include or not, though it usually doesn't make sense to forego possible bitrate savings without good cause. Also note that I said "most decoders" as some only support a few tuned set of levels & profiles. Since there are varying kinds of features, a decoder that supports more of them has to be more complex & flexible/versatile to properly & separately accommodate them (making it more costly, possibly more prone to bugs, likely involving more decoding delay (latency), and - for hardware - probably generating more heat).
So you should get clarity on which specific subsets of Levels & Profiles that your decoders support (hardware and/or software) and tailor your encodes to take advantage of those (with the possibility of future growth in mind). Luckily, newer/more modern decoders almost always incorporate backward-compatibility.

This is a separate issue from the actual bitrate chosen (though this must of course conform to be within the max of those tiers allowed for certain levels).

Scott