In Deliver page Audio section disabled

Hi,
When in the Deliver page in field "Format" I MP4 select then is automatically the Audio section disabled. In my view this was in version 17 not disabled.

Regards, Pius

[Shrinivas Ramani]

In Linux, there are no MP4 conformant audio encoding options available in Resolve. Any rendered MP4s from Resolve was video-only.

With Resolve 18, the audio tab was disabled to make this state clearer.

Hi,
Many thanks for your answer. I know about audio is DR in Linux limited. Anyway in my view in Version 17 was it possible.
Regards, Pius

[Shrinivas Ramani]

To clarify,

It was possible to set audio settings in the render settings for audio, but not to choose audio codecs, or see an audio render for MP4 actually happen.

Note that MOV and other formats don't have this issue. Given the container similarities, you can choose to render an MOV file with audio and rename it to MP4 which commercial systems should accept.

In Linux, there are no MP4 conformant audio encoding options available in Resolve. Any rendered MP4s from Resolve was video-only.

With Resolve 18, the audio tab was disabled to make this state clearer.

Hmm, that does seem quite correct to me. Linear PCM at least worked fine in version 17 under Linux. Now in 18b5 if I have Linear PCM selected in the deliver page audio tab, I get no audio rendered into a Mov file. I can however select MP3 and get audio rendered (the only way to get sound rendered I've found so far).
It would be rather nice to get PCM working again.

I can second what John said. DaVinci Resolve 17 allowed for MP4 (h.264 and h.265) video with Linear PCM (SOWT) encoded audio without issue. That was what I was using for all the videos I made over that time; and it wasn't until Resolve 18 beta came out that I had to find a different video container to use to retain audio for h.264/ h.265 videos (I wound up going to MOV, but it would be nice to have MP4 as an option).

[Dwaine Maggart]

I did a sanity check with 17.4.6 Studio on Linux with an NVIDIA GPU.

And while the Audio tab of the Deliver page Codec dropdown menu is totally blank and has no selections with Format MP4 selected in the Video tab, it does indeed render Linear PCM 48000 Hz audio for both H.264 and H.265 Codec selections.

Fun!

I did a sanity check with 17.4.6 Studio on Linux with an NVIDIA GPU.

And while the Audio tab of the Deliver page Codec dropdown menu is totally blank and has no selections with Format MP4 selected in the Video tab, it does indeed render Linear PCM 48000 Hz audio for both H.264 and H.265 Codec selections.

Fun!

We weren't imagining things!

I started using DR at the end of version 16 exporting almost every project to mp4 since the platforms I use recommend it. So it's behaved like that for a bit. Given mov and mp4 are so similar, the file sizes come out within a few MB over the handful of 5-10 min encodes I've tested. So it's mainly the platform compatibility that makes losing mp4 audio frustrating for me.

I've been reading quite a bit on this the past few weeks since in another thread it was said that MP4 lacks support for LPCM, but I'm having trouble finding anything that says it is explicitly unsupported. The main result for lack of support is from ffmpeg throwing errors. There seems to be mentions in parts of the mpeg-4 specs over the years about PCM audio. For instance, in the mpeg-d spec from 2005 it says

...it could be any of a number of high-performance compression algorithms such as MPEG-1 Layer III, MPEG-4 AAC or MPEG-4 High Efficiency AAC, or it could even be PCM.

It's important to note the context for that was for mpeg surround audio specifically though. There are more recent mentions in draft specs and meeting notes that I could find from around 2015-2018 though.

There's also mention of explicit support for LPCM audio in MP4 files with video in the mpeg-4 ALS spec. Given the age of that I'm not sure how that plays into modern versions of the specifications. Ffmpeg for instance only has decode support for mpeg-4 ALS encoded files, which may explain why it's thrown errors for years.

I'm certainly no expert at reading these specs though. Saying they're hard to navigate is an understatement IMO. Plus the publicly available ones are outdated.

One interesting thing I noticed researching this though is that for the mpeg-4 spec header there is both a 'lpcm' and a 'sowt' tag (actually a few variants for the later), both representing pcm. My Resolve 17 exports have the 'sowt' tag which is what Apple mentions on their QTFF documentation, but the 'lpcm' tag is what's listed on the mp4ra.org codecs list (also maintained by Apple). No clue if that means anything, but caused some confusion till I found an explanation of what 'sowt' was.

I also tried going through previous versions of a few wiki articles to see when and why they added LPCM as supported by mp4, but didn't have much luck past being sent back to the same iso spec references I'd already been through.

So 18 commercial is out now for Linux, and I expected the Mp4 audio issue to be fixed before the commercial version launched, i.e., i was chocking this up to a beta issue that would be resolved, given the number of complaints I saw online about it. But I am very disappointed to see that it is NOT fixed in the commercial version. I will echo the many people, both in this string and in many others, to Blackmagic - this was NOT an issue in 17 - there were no Mp4 audio issues that we ever experienced in 17. We are professional editors so use this everyday. We had to install a Windows version and transfer all ready-to-render projects to that machine in order to deliver our videos. This was, and still is, VERY disappointing. We transferred to Resolve as an org because of the ease of color grading as well as the fact that they supported Linux, which we use for small business security and hosting. Windows does not support small businesses very well for server hosting and security. Therefore Premier was not our first choice. However, now I have to weigh my options as the transfers add an unfeasible amount of time to every project. Very very disappointing Black Magic.

BlackMagic, is not simpler just to make PCM and MP3 audio export to MP4 container? On 18.0.1 mp4 export dont export any audio.

So 18 commercial is out now for Linux, and I expected the Mp4 audio issue to be fixed before the commercial version launched, i.e., i was chocking this up to a beta issue that would be resolved, given the number of complaints I saw online about it. But I am very disappointed to see that it is NOT fixed in the commercial version. I will echo the many people, both in this string and in many others, to Blackmagic - this was NOT an issue in 17 - there were no Mp4 audio issues that we ever experienced in 17. We are professional editors so use this everyday. We had to install a Windows version and transfer all ready-to-render projects to that machine in order to deliver our videos. This was, and still is, VERY disappointing. We transferred to Resolve as an org because of the ease of color grading as well as the fact that they supported Linux, which we use for small business security and hosting. Windows does not support small businesses very well for server hosting and security. Therefore Premier was not our first choice. However, now I have to weigh my options as the transfers add an unfeasible amount of time to every project. Very very disappointing Black Magic.

The is workaround for this. Setup Quicktime render with linear pcm output. Then make second video (menu "add second video output") and select MP4 as format. Then add to render queue. When you render this there being additional file in MP4 format and with this same sound track. Crazy but work.

BlackMagic, is not simpler just to make PCM and MP3 audio export to

I wouldn't mind having 24/48 PCM audio in an MP4 on Windows, either.