Rendering to MXF results in mono audio

[Wayne Waag]

Sorry, I’m not a Guru or Pro, but I don’t think Vegas will do what you’re asking (hope I’m wrong). It sounds as if you want to render to an MXF container that has 1 video stream and 4 audio streams. If that’s the case, I suspect that you would have to render an MXF file with one of the audio streams and then render the three remaining audio tracks as three separate WAV files. You would then have to remux these into a single MXF file having the 1 video and 4 audio streams. You can use FFmpeg to do this. I tried it and it does work–1 video and 4 audio streams within a MXF container. As an aside, I tried a straight MXF render with your project settings. It produced a single stereo file that combined the 4 audio tracks. Interestingly enough, MediaInfo showed them as two mono audio tracks, although when imported into Vegas, it was a single stereo track. In any case, FFmpeg will work. If interested, I can help you with the necessary Command line.

wwaag

Added: The resulting file may not work for you. It plays OK in VLC, but will NOT open in Vegas. Regardless, here is the link to the test file so you can try it out. https://www.dropbox.com/s/akc4knw4zz8sgf1/output.mxf?dl=0

[Herman Erasmus]

Hi Wayne,

Thanks so much for the responce and going to all the trouble to create that test file, which I’m now downloading. Noticed in VLC your audio is mono as well (nice visuals1)

I followed the steps in John’s excellent tutorial, had some underlying issues: installed QuickTime and then the Avid DNxHD codecs. Then things got a bit bitter after configuring the template as he instructs. I actually managed to create a file with stereo audio in it – after trying for who knows how many hours!

However, then I try and modify the audio with Enable Multichannel mapping, it goes to mono audio again.

Can I safely assume, tha whenever you try and do something with audio streams and you are messing about, SVP kind of defaults to Mono audio?

So if I understand you correctly with your suggestion, I need to add the very same audio track (44kHz stereo mp3 file) 4 times into the project, then assign it to Busses A to D, then try and render it again? Customise template, tell it 4 channels, and see what the output brings?

Sorry if I understand wrong or reason way out of line, I’m as inexperienced with SVP as a cockroach in a paint factory!

Also, is it correct that I’m ending up with a file of 2.7gig for a 00:03:05 project? Given the specs that it must be:

File Format: MXF OP1a Codec: DNxHD 8bit 120Mbps
Stored size: 1920*1080 Frame Rate: 25/1
Frame Type: Interlaced/TFF Chroma: 4 2 2
HD Audio: PCM 24bits per sample, 8 channel 48000kHz

[Wayne Waag]

Can I safely assume, that whenever you try and do something with audio streams and you are messing about, SVP kind of defaults to Mono audio?

I suspect that this is indeed the case for MXF. Stereo will render as 2 mono channels (left and right). Thus 4 stereo tracks will render as 8 mono tracks. I redid the little test footage. Here is a screenshot of the timeline.

Here is the link to the re-rendered file, showing the 8 mono tracks and not 4 stereo tracks.

https://www.dropbox.com/s/wqnktoytusg1jsp/mxf%20test%20final.mxf?dl=0

Perhaps someone could confirm that this is indeed the way Vegas works and it is the correct way to proceed. You could use FFmpeg to create the 4 stereo tracks, but from what I now see, I wouldn’t recommend it. You might pose your question on the Vegas pro forum. In any case, good luck.

wwaag

[John Rofrano]

[Herman Erasmus] “File Format: MXF OP1a Codec: DNxHD 8bit 120Mbps”

What you created does not match these specs. They are asking for DNxHD in an MXF container and you are placing it in a MOV container. That’s not the same thing. Vegas Pro is not capable of placing DNxHD in an MXF container so you cannot create this file with Vegas Pro.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[John Rofrano]

[Herman Erasmus] “Get it over to HD – 1920*1080 25fps Interlaced 4:2:2 with PCM 8 channel (4 pairs of stereo) audio: 24 bit, 48000 sample rate. “

Stereo is concept, not a file format. The file format will always have 2 mono tracks. Whether they are interpreted as Left and Right images from a Stereo recording is up to the software that reads it and maps it as such. That’s why Vegas Pro allows you to control the mapping when you read the file back in. If you created a file with 8 channels from your 4 stereo pairs then you’ve created the audio successfully.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Wayne Waag]

[John Rofrano] That’s why Vegas Pro allows you to control the mapping when you read the file back in.

How do you do this? When I read the file with 8 audio channels that I’ve created, it only shows a single stereo track with the first 2 channels? How do I get the other 6 channels and do the assignments?

wwaag

[Herman Erasmus]

I do appreciate the advise and help from the fellow forumites.

John, so I’m basically placing a DNxHD into a MOV container (my last try) and not into a MXF container, if I’m grasping the concept now. How would you reckon do I go about getting this done? I see under Output Format I have options of:
– Panasonic P2 MXF
– Sony MXF
– Sony MXF HDCAM SR

Will there be a preset in there that will work, or do I adopt from your tutotial and create a custom template under one of those MXF options?

Thanks!

[Herman Erasmus]

So to solve my problem, I need to copy the same Stereo Audio track (and not insert it 4 times?), like Wayne has shown here, allocated each to a different Bus, and render it Multichannel Mapping Enabled, to get 4 pairs of stereo in the output file?

[John Rofrano]

[Wayne Waag] “How do I get the other 6 channels and do the assignments?”

Two ways:

(1) Copy the audio track 3 more times. Right-click on the 1st copy, select Channels and then Channels 3/4. Right-click on the 2st copy, select Channels and then Channels 5/6. Right-click on the 3st copy, select Channels and then Channels 7/8. You now have 4 tracks with 8 channels mapped to 4 stereo pairs (1/2, 3/4, 5/6, 7/8).

(2) Go to Options | Preferences | General and check Import MXF as multichannel. Now drop the MXF file onto the timeline and you will get 8 mono tracks. Do the same as option (1) and right-click the first 4 audio tracks one by one and select Channels 1/2, 3/4, 5/6, 7/8. Then delete the last 4 audio tracks (they are not needed)

Notice that you can do alternate channel mappings. For example you can map mono channels 2/3 or 4/5 as stereo. So if your first track was mono and your next two were stereo you can leave 1 as mono and make 2/3 stereo. This is why when you send a show off for broadcast they request that the Slate contain the audio channel mappings so that they know how interpret them correctly.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[John Rofrano]

[Herman Erasmus] “Will there be a preset in there that will work, or do I adopt from your tutotial and create a custom template under one of those MXF options? “

I’m not sure if you read my other post but Vegas Pro cannot produce an MXF file with the DNxHD codec in it. It simply can’t be done with Vegas Pro.

I believe that Adobe Premiere Pro can create files using the Avid DNxHD codec in an MXF OP1a container.

~jr

http://www.johnrofrano.com
http://www.vasst.com