Blackmagic Forum

Posted: **Tue Nov 29, 2022 10:41 am**

Hi there,

I´m having trouble with some video files in an quite old format:

HDV files with 4 ch audio.

Is there any chance, to get support for this file type, or there maybe any known workaround to get all 4 audio channels into resolve?

The files are recorded with a sony hvr-s270 hdv cam. One of a few hdv models, supportet 4 channel audio.
In playback mode the cam shows all 4 audio channels. The same files imported in resolve are only stereo audio.

After some research, I found the information that channel 3 and 4 are hidden in somy way in the files, for backwards compatibility. So most of the Software will only "see" two audio Channels.

Is there any chance, support for this quite old format will be addet, to process old footage?

Kind regards,
Christian

Posted: **Tue Nov 29, 2022 1:23 pm**

Can u publish a link to two clips so we can review?

Posted: **Tue Nov 29, 2022 2:44 pm**

Did you try changing audio track type to "adaptive 4" and see if they appear.

Posted: **Tue Nov 29, 2022 3:06 pm**

Thank you for your replies!

Later on I will upload a test file with 4 ch audio.

I tried adaptive 4 channel mode, but it doesnt work.

Greetings!

Posted: **Tue Nov 29, 2022 6:57 pm**

Hi there,

I´ve done some test clips.

First a color bar picture with 1khz sine on all 4 channels. The second clip contains spoken channel numbers. There is a little space between each channel, caused by plugging the same mic in every input of the cam.

All clips are done with the SONY HVR-S270e and attached HVR-MRC1 CF Recorder.

I tried to post a dropbox Link into this post, but I´m not allowed to post URLs. So I will try, to send you a pm with the dropbox link.

Kind Regards
Christian

Posted: **Tue Nov 29, 2022 8:22 pm**

The only way HDV allowed 4 tracks and this camera, was in 12 bit 32KHz. I am not sure Resolve will even recognise 12bit 32KHz tracks, since you would need to set up such a project, I think. You may have to transcode first (to 16bit 48KHz) if you can find a way of doing it.

Posted: **Wed Nov 30, 2022 2:18 am**

Steve Fishwick wrote:The only way HDV allowed 4 tracks and this camera, was in 12 bit 32KHz. I am not sure Resolve will even recognise 12bit 32KHz tracks, since you would need to set up such a project, I think. You may have to transcode first (to 16bit 48KHz) if you can find a way of doing it.

That is not correct. 32kHz 4 channel audio tracks was a thing of DV standard, not HDV.

After some digging I found this interesting post from 2009:

https://www.dvinfo.net/forum/sony-hvr-z ... ost1262442

MPEG2 uses payload IDs inside the TS... and it seems that all four channels are held within the same PID instead of being broken into two seperate PIDs... I'm going to try and split the data a little later today by using a demuxer and then a specialised second demuxer. Standard behaviour is to put mono or stereo tracks into seperate PIDs, HDV doesn't seem to do this. The software only expects two channels and doesn't have any more PIDs to work with... so it drops the extra data.

UPDATE :
There's a reason the specification states that the codec used changes from MPEG1 Layer I to MPEG2... and that's because MPEG1 doesn't support multi-channel.

"
MPEG-2/Multichannel has the following properties:
# up to 5 full range audio channels and an LFE-channel (Low Frequency Enhancement <> subwoofer)
# sample rates the same as those of MPEG-1
"
MPEG AUDIO FRAME HEADER

UPDATE :

Demux complete and I've found the problem!

The frame header coming out of the camera is set incorrectly.

My camera is sending this : 11111111 11111100 11100100 00000100
.......................................SYNC BYTE..........................channels

The two bolded bits define the channel structure as stereo... which is why editing applications drop the additional channels. It should be possible to fix the problem by changing the frame headers.

UPDATE :

This is evil!!!!

From WikiPedia : http://en.wikipedia.org/wiki/MPEG_Multichannel

"
MPEG Multichannel is an extension to the MPEG-1 Layer II audio compression specification, as defined in the MPEG-2 standard ISO/MPEG IS-11172,[1] which allows it provide up to 5.1-channels (surround sound) of audio. To maintain backwards compatibility with the older 2-channel (stereo) audio specification, it uses a channel matrixing scheme, where the additional channels are mixed into the two backwards compatible channels. Extra information in the data stream (ignored by older hardware) contains signals to process extra channels from the matrix.[2]"

Posted: **Wed Nov 30, 2022 2:31 am**

Maybe Sony Catalyst Browse will decode them. https://www.sonycreativesoftware.com/download/catalystbrowse

Posted: **Wed Nov 30, 2022 6:27 am**

Robert Niessner wrote:That is not correct. 32kHz 4 channel audio tracks was a thing of DV standard, not HDV.

Robert, you are absolutely right but I took this information from the Sony HVR-S270 manual, where it's called 4CH/FS32K recording. It makes no mention of HDV/DV. Further, I have a JVC BR-HD50 HDV deck sat here on my desk and I double-checked that - 2ch HDV/up to 4Ch DV. HDV tape did not have 4 channels, that is true. But the OP mentions HDV with 4 channels. Therefore I think these clips must be actually DV. Unless the Sony camera has a way of non-standardly combining the DV sound format with HDV picture. In any case and according to that camera's manual, they will be 32KHz, since the total bandwidth of DV/HDV tape could not accommodate 4 tracks at pcm (or mpeg) 16bit 48KHz. The information you found does not refer to any camera format but appears to be MPeg-2 for DVD and such.

I did edit my post but I should have been more careful in checking. Back in the day (and I still have it) I shot a lot of material for both corporate and broadcast on DV and HDV, with the JVC HD101E. It does not have 4 inputs but before that I had a Canon XL1s with an optional XLR back that did have 4 inputs for DV. My broadcast Sony DSR-570 DVCams did not have 4CH inputs though as I can remember.

Posted: **Wed Nov 30, 2022 7:06 am**

Steve, if you follow the link in my previous post you'll see the guy is really talking about HDV.
In HDV the audio tracks were never uncompressed PCM like with DV, they were always compressed - so therefore I do not see a problem getting 4 channels stuffed into the 25 MBit/s of the tape.
But it must have been very unusual.

Posted: **Wed Nov 30, 2022 7:39 am**

Robert Niessner wrote:In HDV the audio tracks were never uncompressed PCM like with DV, they were always compressed - so therefore I do not see a problem getting 4 channels stuffed into the 25 MBit/s of the tape.

Robert, it simply doesn't have the space left over for that. HDV 1080i tape used all the existing DV 25mb/s bandwidth (including sound) for MPeg picture, the remaining space could only fit 2 x 384mbps compressed MPEG-1 Layer II 16bit 48KHz tracks. HDV 720p (a la JVC) was different, with theoretically more space, though never 4 tracks either. It could be possible I suppose but I've never heard of it. In any case I only quickly perused the Sony manual, perhaps the definitive answer, in this instance is there? Though I couldn't find it, except the 32KHz reference I mentioned.

Later solid state cameras, such as JVC, could accommodate 4 pcm tracks plus a 'HDV' picture stream at either up to 35mb/s, though I don't think they had the option of MPEG-1 Layer II 384mbps compressed audio, as well. Maybe the reference, you found, was referring to that?

Posted: **Wed Nov 30, 2022 11:24 am**

Steve, I've found this from Canon's knowledge base about the XL-H1:

HDV Recording

The audio transfer rate is 384 Kbps when recording on 2 channels, and 384 Kbps (192 Kbps / 2 channels) when recording on all 4 channels. The sampling frequency is 48 kHz in all modes. Audio dubbing cannot be performed with this camcorder.

SD Recording

You can choose to record in 16 bit audio mode (sampling frequency 48 kHz), or 12 bit audio mode (sampling frequency 32 kHz). When recording in 12 bit audio mode, you can further select to record on only 2 channels - leaving two channels free for audio dubbing later; or to record on all 4 channels simultaneously.

Source: https://support.usa.canon.com/kb/index? ... =ART125203

So for two channels it is using 192 Kbps per channel and for four channels it goes down to 96 Kbps per channel.

Posted: **Wed Nov 30, 2022 1:29 pm**

As I mentioned Sony Catalyst may be the easiest way to find out and should decode whatever it is and I expect Vegas would also present correctly too. My DV decks HDR1000 etc have Stereo 1 and stereo 2 controls with mix and dub so DV certainly did have 4 channel capability.

Posted: **Wed Nov 30, 2022 1:41 pm**

Robert Niessner wrote:So for two channels it is using 192 Kbps per channel and for four channels it goes down to 96 Kbps per channel.

Well found, Robert. Then perhaps it is so for the Sony? Though it didn't mention that in the manual. There was a bit of proprietary deviations from the standards of HDV, by the each of the manufacturers, as I recall. As Ron suggests the OP will most likely have to transcode outside of Resolve.

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