Any quality benefit saving to different codec?

Rich Parry wrote on 9/27/2015, 7:40 PM

If I start with a video with these specifications (i.e., Sony FDR AX100 XAVC S Long) …
• 60 Mbps Bit Rate
• 4:2:0 Subsampling
• 8 bit Bit Depth

Then save it as Sony XAVC Intra with these specifications
• 110 Mbps Bit Rate
• 4:2:2 Subsampling
• 10 bit Bit Depth

Isn’t it true that nothing is gained in quality. Specifically, changing from 60 to 110 does nothing, changing subsampling from 4:2:0 to 4:2:0 does nothing, and changing 8 bits to 10 bits doesn’t nothing. Changing codecs can’t improve the quality over what is already have, agree?

There may be some advantages with editing but as far as quality goes, there is nothing to be gained by saving to a different codec, right?

XAVC Intra results in a file 3 to 4 times larger than XACX S Long and I can see no reason to save to the Intra codec, can you?

Rich

Comments

TheHappyFriar wrote on 9/27/2015, 7:48 PM

You can never get better then what you put in but you can easily get worse. If the video is reencoded there is ALWAYS the possibility of loss, so even reencoding from 30mbs to 110mbs could reduce the quality.

musicvid10 wrote on 9/28/2015, 8:12 AM

No, upsampling does not improve on, or reverse native encoding losses.

In the case of RGB or 10 bit source, a 10 bit intermediate is better than 8 bit, even though the destination encoder delivers playable 8 bit. This is due to YUV lossiness and dithering.

Former user wrote on 9/28/2015, 9:03 AM

Each time you compress there is some additional loss of quality, so you are right in that going to a higher bitrate or different codec will not improve the quality of the source, but it can sometimes keep additional quality loss to a minimum.

Chienworks wrote on 9/28/2015, 9:24 AM

"but it can sometimes keep additional quality loss to a minimum"

But it will still be more quality loss than sticking with the original.

Former user wrote on 9/28/2015, 9:26 AM

Chienworks, of course. If that is an option.

OldSmoke wrote on 9/28/2015, 11:53 AM

@Rich

There is a slight advantage when downsizing 4K from your AX100 to HD1080. You can give that a try with the free Catalyst Browse or if you have Catalyst Prepare. The resulting XAVC Intra HD files are 10bit 422 and look stunning in a 32bit full range project. While this article is about the GH4, I found it works well with the AX100 and XAVC-Intra too.