Is ’focal length’ in the mp4 file for sony cameras such as a6400,a7r4,a7m3

[Jhe]

I know rtmd data in A7M4 A7R5 has focallength every frame. But not in a6400,a7r4,a7m3 camera which don't contain gyroscope data. How can i get focallength in these cameras?

[Phil Harvey]

If you can post a link to sample videos, we can take a look to see if this information is perhaps available.

- Phil

[Jhe]

Thanks for your reply! 
I shared a sony a6400 video which shooted at 16mm.
https://drive.google.com/file/d/1Uncq--pKGhw_ZcWfEagmejLMzrKkALOf/view?usp=sharing

[Phil Harvey]

There is a lot of unknown timed metadata in this video.  It is likely that the focal length is in there, but it isn't stored as a simple integer, so will require more sample to decode.  Could you upload a few (short) samples shot at different known focal lengths?  And possibly one where the focal length changes between 2 known values during the video (do you have a zoom lens?).

- Phil

[Jhe]

There is a lot of unknown timed metadata in this video.  It is likely that the focal length is in there, but it isn't stored as a simple integer, so will require more sample to decode.  Could you upload a few (short) samples shot at different known focal lengths?  And possibly one where the focal length changes between 2 known values during the video (do you have a zoom lens?).

- Phil

Yes I have zoom lens.

https://drive.google.com/drive/folders/1cicxHP0Lwj6GM_FvJ0LZ3gt5U2wQ6Ujl?usp=drive_link

1.C0015.MP4： Camera: Sony A7M3    Lens: Tamron 28mm-75mm
2.C0021.MP4： Camera: Sony A7M3    Lens: Sony   24mm-70mm

[Phil Harvey]

I got the samples and have gone through them quickly.  I've discovered another 2 locations where ISO is stored (not very helpful), but can't see the focal length anywhere.  The tag Sony_rtmd_0x8001 is interesting, but doesn't seem to be related to focal length.  A post from forum15856 mentions this is related to focus distance.  A post from forum14315 thinks that the focus distance is stored in Sony_rtmd_0x8004 and Sony_rtmd_0x8005, but your videos don't have this tag.

You can see all this unknown information with exiftool -ee -u "-sony_rtmd*" FILE

- Phil

[Jhe]

I got the samples and have gone through them quickly.  I've discovered another 2 locations where ISO is stored (not very helpful), but can't see the focal length anywhere.  The tag Sony_rtmd_0x8001 is interesting, but doesn't seem to be related to focal length.  A post from forum15856 mentions this is related to focus distance.  A post from forum14315 thinks that the focus distance is stored in Sony_rtmd_0x8004 and Sony_rtmd_0x8005, but your videos don't have this tag.

You can see all this unknown information with exiftool -ee -u "-sony_rtmd*" FILE

- Phil

Yes 0x8001 may not useful. But i just want to get the first frame focallength(like canon ,nikon ), it may not be in rtmd. rtmd_0x8004 is only in newer cameras like A7M4,A7R5,A7C2 etc.

[Phil Harvey]

Other than the XML junk, there isn't any useful static metadata that I can see, so I think our only hope was for the rtmd metadata, but I don't see it there.

- Phil

[Jhe]

Other than the XML junk, there isn't any useful static metadata that I can see, so I think our only hope was for the rtmd metadata, but I don't see it there.

- Phil

Thanks for your reply again. Maybe Sony does not record this data in video.