XAVC-I vs XAVC S-I

B

bengiles

Well-known member
Hi All.

Sorry, haven't been here for a while - but I've been lurking...

I can't find a Google answer to this - the difference between the XAVC-I on the FX6 and XAVC S-I on the A7iv.

The UHD 4K specs look similar in terms of bitrate (ie up to 600 Mb/s):

XAVC-I
DCI 4K (4096 x 2160) from 1 to 59.94 fps [240 to 600 Mb/s VBR]
UHD 4K (3840 x 2160) from 1 to 59.94/100/119.88 fps [240 to 600 Mb/s VBR]
1920 x 1080p from 1 to 59.94/100/119.88/150/179.82/200/239.76 fps [89 to 223 Mb/s VBR]


H.264/XAVC S-I 4:2:2 10-Bit
UHD 4K (3840 x 2160) at 23.98/25/29.97/50/59.94 fps [240 to 600 Mb/s]
1920 x 1080p at 23.98/25/29.97/50/59.94 fps [89 to 222 Mb/s]

Does anyone know definitively please? Is it just Sony marketing speak?

Is it just essentially the addition of DCI to XAVC-I spec?

Cheers,

Ben.
 
The compression quality is supposed to be the same. The main difference is that XAVC-I comes in an .MXF wrapper and XAVC-S comes in a consumer-friendly .MP4 wrapper. There may also me differences in the number of audio channels.
 
As Doug Says. Same, same in the Intra frame codec but with different wrapper. MXF wrappers have the ability to carry more sub code data. The biggest difference is in the XAVC-L codec. In 4K/UHD that is an 8-bit codec on the FX6 and 9 but is a higher bit rate 10-bit codec on the A7iii, A7iv, FX3 and 30.

Up to 4 audio channels available on the A7iv and A7siii, FX3 and also the FX30 I believe. These models have the ability to record up to four channel audio in video, rather than just two. To do this, you need the XLR-K3M adapter. This features two XLR inputs and a 3.5 mm stereo input. Though, the left and right channel of the 3.5 mm input can't be adjusted independently. There's an option in the Setup menu to select which inputs are output to the two monitoring channels. This includes the option to hear channels 1 and 3 in one ear and 2 and 4 in the other, for full four-channel monitoring.

Chris Young
 
bengiles said:
):

XAVC-I
DCI 4K (4096 x 2160) from 1 to 59.94 fps [240 to 600 Mb/s VBR]
UHD 4K (3840 x 2160) from 1 to 59.94/100/119.88 fps [240 to 600 Mb/s VBR]
1920 x 1080p from 1 to 59.94/100/119.88/150/179.82/200/239.76 fps [89 to 223 Mb/s VBR]
Click to expand...

I know this was copied in from elsewhere, but shouldn't that say CBR rather than VBR?

I have nothing to add to the other comments except that from what I can see, they have equal visual quality. And they seem to be equally playback-friendly both for me and for my editors
 
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