YouTube's 5.1 sound volume

Den24601 wrote on 3/6/2022, 7:51 AM

We’ve noticed that our 5.1 projects on YouTube play much quieter than our 2-channel projects, even the exact same project.  All 5.1 channels perform as mixed on YouTube, but the overall volume is significantly reduced compared to its local, 5.1 playback.  These are all family and kid projects, just for fun, not a big deal, here today and gone tomorrow, but I’m curious why it’s happening and if there is a workaround? Both our stereo and 5.1 projects are rendered using Voukoder and VP18, AAC, and AC3, respectively, and we do change AC-3  to 640 k/Bits.  Our solution is to double the receiver’s volume when playing 5.1 vs. 2-channel projects via YouTube.    Is this normal YouTube processing of 5.1 material?

Comments

rraud wrote on 3/6/2022, 10:12 AM

Is this normal YouTube processing of 5.1 material?

I would never upload a multi-channel mix to YouTube. A simple stereo mix is best in this case. YT probably down-mixes the audio in the re-encode process which forks up the audio (and video).

Den24601 wrote on 3/6/2022, 1:45 PM

The 5.1 mix works perfectly, YouTube preserves all channels, including LFE, but it's just a much lower volume than the stereo version.

EricLNZ wrote on 3/6/2022, 4:37 PM

Have you asked YouTube?

Den24601 wrote on 3/7/2022, 10:46 AM

I have no idea how to ask Youtube. I have noticed that it plays audio as EC-3 on my smart TV, but it's only stereo using Opus when played via my Firefox browser. No big deal, I thought maybe someone had an explanation. Youtube just began supporting surround last August, so perhaps they are still working out the details.

Former user wrote on 3/7/2022, 9:50 PM

Youtube has surround audio but not AC3, and I get the opus audio in browser also. There may be a way of forcing surround on browser. The 5.1 shows as an audio option on a Youtube downloader, this must be what you're hearing on your TV

Audio
ID                                       : 1
Format                                   : AAC LC SBR
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication
Commercial name                          : HE-AAC
Format settings                          : NBC
Codec ID                                 : mp4a-40-5
Bit rate mode                            : Constant
Bit rate                                 : 192 kb/s
Channel(s)                               : 6 channels
Channel layout                           : C L R Ls Rs LFE
Sampling rate                            : 48.0 kHz
Frame rate                               : 23.438 FPS (2048 SPF)
Compression mode                         : Lossy
Title                                    : ISO Media file produced by Google Inc.
Language                                 : English
Default                                  : Yes
Alternate group                          : 1

Former user wrote on 3/7/2022, 11:45 PM

We’ve noticed that our 5.1 projects on YouTube play much quieter than our 2-channel projects, even the exact same project.  All 5.1 channels perform as mixed on YouTube, but the overall volume is significantly reduced compared to its local, 5.1 playback.  These are all family and kid projects, just for fun, not a big deal, here today and gone tomorrow, but I’m curious why it’s happening and if there is a workaround?

I missed your main complaint. Try the Stereo + 5.1 audio that youtube recommend. The opus audio should be your uploaded stereo track, and 5.1 audio stays 5.1, there is no down conversion of 5.1 to stereo which must cause the volume issue. Encode your video with 5.1 audio, then encode a separate stereo audio track. Mux together with Mkvtoolnix to mp4 container. Although mkv is more 'legal' for this project I've heard YT has more restrictions on mkv than mp4 as far as codecs and formats

I haven't tried this but if you do in the future, let us know if that solves low volume issue on browser while the surround audio on TV remains the same

 

Former user wrote on 3/8/2022, 5:12 AM

I tried Stereo + 5.1 upload and it doesn't work. It looks like it used to but not anymore. The uploaded stereo track disappears, with stereo track from youtube being down converted 5.1 audio. I do notice YouTube reduced the playback volume by 7.7db but that is still in the realms of normal. The way you described your 5.1 downmix is much lower in volume.

The 5.1 audio I uploaded was converted to both dolby digital and dolby digital plus, so your TV is correct. No idea what they do with the other 5.1 audio formats created

This is the audio media info for my upload

Audio #1
ID                                       : 2
Format                                   : PCM
Format settings                          : Little / Signed
Codec ID                                 : A_PCM/INT/LIT
Duration                                 : 20 s 954 ms
Bit rate mode                            : Constant
Bit rate                                 : 705.6 kb/s
Channel(s)                               : 1 channel
Sampling rate                            : 44.1 kHz
Bit depth                                : 16 bits
Default                                  : Yes
Forced                                   : No

Audio #2
ID                                       : 3
Format                                   : PCM
Format settings                          : Little / Signed
Codec ID                                 : A_PCM/INT/LIT
Duration                                 : 20 s 960 ms
Bit rate mode                            : Constant
Bit rate                                 : 4 608 kb/s
Channel(s)                               : 6 channels
Sampling rate                            : 48.0 kHz
Bit depth                                : 16 bits
Default                                  : No
Forced                                   : No

The downmixed opus stereo seems fine, so no need for the separate uploaded stereo track in this test example.

Den24601 wrote on 3/8/2022, 8:23 AM

It is 5.1 surround using EC-3 from YouTube when using my TLC Smart TV (with Roku YouTube app) connected to my 5.1 amplifier. However, I don't notice any volume change when playing it via YouTube on just the TV, where it's stereo (but still EC-3), bypassing the surround receiver. Perhaps the sound-volume issue is partially device-related to my equipment. Until YouTube rolls out more devices, like browsers, I can't tell. I do know the Youtube 5.1 volume level requires almost double the volume on my 5.1 amplifier, but that same file's volume is normal when played back locally as 5.1 surround. Again, it may be related to my YT and my TCL TV. From what I've researched, no one has successfully gotten YT 5.1 from a browser yet.