MP4 video with PCM 2.0 stereo sound: DOES NOT PLAY AUDIO

User Help for Mozilla Firefox
Post Reply
DSperber
Posts: 155
Joined: September 30th, 2012, 1:52 pm

MP4 video with PCM 2.0 stereo sound: DOES NOT PLAY AUDIO

Post by DSperber »

For some reason, FF 111.0 (and many previous versions before this one) does not deliver audio when playing an MP4 video file with PCM 2.0 audio inside. The speaker icon is "X'd out" and cannot be un-X'd. Video file can be local MP4 file, or a URL. Video plays fine, just audio is suppressed.

I have already gone to Tools -> Settings -> Privacy & Security -> Autoplay -> Settings -> Default for all websites -> Allow audio and video, so this shouldn't be the issue.

Note that identical local file and URL plays BOTH audio and video perfectly using Edge.

Also, the MP4 file doesn't contain audio in either AC3 or DD+. It is specifically created with PCM audio in order to be playable universally, including on all phones and computers. The problem seems unique to FF.

I will be glad to provide (via PM) the URL for a small sample video clip for you to try for yourself if you don't have one of these video files of your own.
redwolfe_98
Posts: 402
Joined: September 26th, 2008, 2:13 am
Location: South Carolina, USA

Re: MP4 video with PCM 2.0 stereo sound: DOES NOT PLAY AUDIO

Post by redwolfe_98 »

doing a search for "mp4 pcm file" i find articles saying that pcm is not compatible with mp4.
find answers at "Mozilla Support":
https://support.mozilla.org/en-US/products/firefox
DSperber
Posts: 155
Joined: September 30th, 2012, 1:52 pm

Re: MP4 video with PCM 2.0 stereo sound: DOES NOT PLAY AUDIO

Post by DSperber »

Never heard of this, that the MP4 container cannot hold PCM audio.

Again... this MP4/PCM file is 100% playable with all other "media player" apps, not to mention other browsers. It is just FF which can't handle the sound. I think the problem here is "FF as the player", which appears unwilling to accept PCM audio inside the MP4 container.

That is exactly the point of my thread, to mention this and ask if it should not be corrected.

Image

Code: Select all

General
Complete name                            : \\Dfw\f\MyVideos\Real Time S02E08_March 17, 2023 Noa Tishby.mp4
Format                                   : MPEG-4
Format profile                           : QuickTime
Codec ID                                 : qt   0000.02 (qt  )
File size                                : 547 MiB
Duration                                 : 11 min 31 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 6 635 kb/s
Writing application                      : VideoReDo (Lavf58.29.100)

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L3.1
Format settings                          : CABAC / 4 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 4 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 11 min 31 s
Bit rate mode                            : Variable
Bit rate                                 : 5 100 kb/s
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 29.970 (30000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.185
Stream size                              : 419 MiB (77%)
Writing library                          : x264 core 160 r3000
Encoding settings                        : cabac=1 / ref=4 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=4 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=12 / lookahead_threads=3 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=1 / keyint=60 / keyint_min=6 / scenecut=0 / intra_refresh=0 / rc_lookahead=20 / rc=abr / mbtree=1 / bitrate=5054 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=5099 / vbv_bufsize=2550 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
Menus                                    : 3
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : PCM
Format settings                          : Little / Signed
Codec ID                                 : sowt
Duration                                 : 11 min 31 s
Bit rate mode                            : Constant
Bit rate                                 : 1 536 kb/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Bit depth                                : 16 bits
Stream size                              : 127 MiB (23%)
Language                                 : English
Default                                  : Yes
Alternate group                          : 1
Menus                                    : 3

Menu #1
ID                                       : 3
Format                                   : txet
Codec ID                                 : txet
Duration                                 : 11 min 31 s
Language                                 : English
Menu For                                 : 1,2

Menu #2
00:00:00.000                             : Chapter 1

User avatar
therube
Posts: 21703
Joined: March 10th, 2004, 9:59 pm
Location: Maryland USA

Re: MP4 video with PCM 2.0 stereo sound: DOES NOT PLAY AUDIO

Post by therube »

PCM 2.0 audio
Container aside, maybe FF simply does not support PCM audio?

Sample file, https://software-download.name/sample-m ... nload.html.
(In SeaMonkey, FF, you'll get video but no audio.)


(As far as the container, while you may have pcm in a mp4, possibly, most software will not allow you to do that.
ffmpeg -i mov.mov -c copy out.mp4 - fails - pcm not supported in mp4
mkv has no such issue
ffmpeg -i mov.mov -c copy out.mkv)
Fire 750, bring back 250.
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.19) Gecko/20110420 SeaMonkey/2.0.14 Pinball CopyURL+ FetchTextURL FlashGot NoScript
Lotesdelere
Posts: 32
Joined: March 13th, 2013, 4:38 am

Re: MP4 video with PCM 2.0 stereo sound: DOES NOT PLAY AUDIO

Post by Lotesdelere »

It's a QuickTime file, therefore it's not a 'pure' MP4 container but a MOV one and the SOWT Little Endian PCM Audio Codec of these files can be played by VLC and MPV, thus by FFmpeg ;-)
There are even sample files on ffmpeg.org, like this one:
https://samples.ffmpeg.org/mov/qtaudio/ ... L-sowt.mov

So Firefox could and should play them.
User avatar
therube
Posts: 21703
Joined: March 10th, 2004, 9:59 pm
Location: Maryland USA

Re: MP4 video with PCM 2.0 stereo sound: DOES NOT PLAY AUDIO

Post by therube »

Does that file play in Chrome?


It is not unreasonable that a browser may not play all formats that a media player may happen to be able to play.


If it does work in Chrome, then file a bug & see what happens?
(Something working in Chrome & not in FF is a great impetus to Mozilla to do something ;-).)
Fire 750, bring back 250.
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.19) Gecko/20110420 SeaMonkey/2.0.14 Pinball CopyURL+ FetchTextURL FlashGot NoScript
Post Reply