The VideoLAN Forums

Posted: **22 Jun 2020 10:25**

Hello all,

just today, I encountered a few MP4 video files that would not play with audio on VLC on Linux.

VLC version:

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VLC media player 3.0.10 Vetinari (revision 3.0.10-0-g7f145afa84)
VLC-Version 3.0.10 Vetinari (3.0.10-0-g7f145afa84)

Linux distribution used:

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DISTRIB_ID=ManjaroLinux
DISTRIB_RELEASE=20.0.3
DISTRIB_CODENAME=Lysia
DISTRIB_DESCRIPTION="Manjaro Linux"

Codec information:

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Codec: MPEG AAC Audio (mp4a)
Language: English
Type: Audio
Channels: 3F2R/LFE
Sample Rate: 48000 Hz
Bits per Sample: 32

Strange enough, there is not a lot of information found on the net. As I have a few videos where the audio sample rate is set to 44100 Hz (all other parameters the same as in the example), which all play flawlessly, I guessed the sample rate was the problem.

Instead, the solution is to change the preferred decoder to avcodec (see here and here).

Question is: What advantages does faad have over avcodec that it is used as the default in VLC?

Thank you very much for all insights in advance and kind regards,

DAC324

Posted: **29 Jun 2020 12:25**

Update:

This behavior also occurs with the latest VLC version 3.0.11 on Linux.
It looks like FAAD2 is not able to decode this kind of files as 48 kHz sample rate seems to be out of spec for this decoder.

InTheWings kindly advised me to have a look at the possibility of libfaad.so being replaced.

Unfortunately, the latest version of libfaad for Linux appears to be 2.0.0, and there seems to have been no update since 2017, according to the source available for download at the Audiocoding site.

Does anybody know if a newer libfaad version exists for Linux?

Thank you very much and kind regards,
DAC324

Posted: **29 Jun 2020 13:08**

VLC (on Windows or macOS) uses FAAD 2.9.2. This is also available on Debian...

Posted: **29 Jun 2020 15:18**

VLC (on Windows or macOS) uses FAAD 2.9.2. This is also available on Debian...

Thank you very much for this information.
Indeed, I must admit that I am a little bit confused:

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$ pacman -Qs faad2
local/faad2 2.9.2-1
    ISO AAC audio decoder

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$ ls -l /usr/lib/libfaad*
lrwxrwxrwx 1 root root     20  5. Mai 11:58 /usr/lib/libfaad_drm.so -> libfaad_drm.so.2.0.0
lrwxrwxrwx 1 root root     20  5. Mai 11:58 /usr/lib/libfaad_drm.so.2 -> libfaad_drm.so.2.0.0
-rwxr-xr-x 1 root root 251800  5. Mai 11:58 /usr/lib/libfaad_drm.so.2.0.0
lrwxrwxrwx 1 root root     16  5. Mai 11:58 /usr/lib/libfaad.so -> libfaad.so.2.0.0
lrwxrwxrwx 1 root root     16  5. Mai 11:58 /usr/lib/libfaad.so.2 -> libfaad.so.2.0.0
-rwxr-xr-x 1 root root 264088  5. Mai 11:58 /usr/lib/libfaad.so.2.0.0

Looks like the package version available here is indeed 2.9.2-1 but it installs libfaad*.2.0.0

Also, I had a look in the FAAD2 source. In decoder.c, it says:

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hDecoder->config.defSampleRate = 44100; /* Default: 44.1kHz */

But on the other hand, 48 kHz appears to be a valid sample rate, anyway (common.c):

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/* Returns the sample rate based on the sample rate index */
uint32_t get_sample_rate(const uint8_t sr_index)
{
    static const uint32_t sample_rates[] =
    {
        96000, 88200, 64000, 48000, 44100, 32000,
        24000, 22050, 16000, 12000, 11025, 8000
    };

Looks like there is a bug in FAAD2 (at least on Linux) preventing it to handle the 48 kHz sample rate properly.

Kind regards,
DAC324

Posted: **06 Jul 2020 10:14**

Looks like the package version available here is indeed 2.9.2-1 but it installs libfaad*.2.0.0

2.0.0 is the API/ABI numbering, not library version

Posted: **21 May 2021 15:36**

Hello,

just to provide some update. Meanwhile, faad2 has been updated to package version 2.10.0-1 but the problem with the sample rate of 48 kHz not being processed properly, still persists.

Kind regards,
DAC324

Posted: **21 May 2021 16:00**

Hello,

just to provide some update. Meanwhile, faad2 has been updated to package version 2.10.0-1 but the problem with the sample rate of 48 kHz not being processed properly, still persists.

Kind regards,
DAC324

Provide a way to reproduce the issue

Posted: **25 May 2021 13:33**

Provide a way to reproduce the issue

At first, you need a video file with the following specifications:

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Stream 0
Codec: H264 - MPEG-4 AVC (part10) (avc1)
Type: Video
Video Resolution: 1280 x 720
Buffer Size: 1280 x 720
Frame Rate: 23.976032
Decoded Format: <empty>
Alignment: Upper left
Basic Colors: ITU-R BT.709
Color transmission function: ITU-R BT.709
Color Space: ITU-R BT.709 area
Color saturation shift: Left

Stream 1
Codec: MPEG AAC Audio (mp4a)
Language: English
Type: Audio
Channels: Stereo
Sample Rate: 48000 Hz
Bits per Sample: 32

When such a video file is started, I only get video but no audio.
What you will have to do is:

In Tools > Settings (all) > Input/Codecs > Videocodecs > List of preferred decoders, you will have to enter

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avcodec

and save. With that setting, the video in question plays fine, including audio. As soon as this avcodec entry is omitted, there is again silence instead of the audio.

Interesting: As soon as avcodec is enabled, the codec information changes from

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Channels: Stereo

to

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Channels: 3F2R/LFE

Looks like the default faad decoder is not able to determine the channel configuration and hence, just does not play any audio at all.

Posted: **26 May 2021 22:08**

As I cannot update my previous posting, I add this information here:

Without avcodec included in the list of preferred decoders, Video playback also stutters and has color artifacts (vlc 4.0.0).

Posted: **27 May 2021 09:55**

no file no test no fix

Posted: **27 May 2021 11:16**

no file no test no fix

Problem is that the video file in question is copyright protected. I did a search for a free sample video file with the same specifications (as shown in VLC) but there, the error did not occur. Is there a way to get more comprehensive audio/video format information than the one shown in VLC's codec information window?
I started vlc from terminal with this video and get:

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VLC media player 4.0.0-dev Otto Chriek (revision 03674ae)
[h264 @ 0x7fb41deb2b40] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 0x7fb41deb2b40] nal_unit_type: 8(PPS), nal_ref_idc: 3
[h264 @ 0x7fb41deb2b40] nal_unit_type: 5(IDR), nal_ref_idc: 3
[swscaler @ 0x7fb4140e7440] Forcing full internal H chroma due to input having non subsampled chroma
[h264 @ 0x7fb41deb2b40] Format yuv420p chosen by get_format().
[h264 @ 0x7fb41deb2b40] Reinit context to 1280x720, pix_fmt: yuv420p
[h264 @ 0x7fb41deb2b40] no picture 
[h264 @ 0x7fb41defb900] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 2
[h264 @ 0x7fb41defb900] no picture 
[h264 @ 0x7fb41df18600] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 2

Log file is here.

With avcodec set in the list of preferred decoders, I get the following (similar) output in the terminal:

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LC media player 4.0.0-dev Otto Chriek (revision 03674ae)
[h264 @ 0x7f3879eb2b40] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 0x7f3879eb2b40] nal_unit_type: 8(PPS), nal_ref_idc: 3
[h264 @ 0x7f3879eb2b40] nal_unit_type: 5(IDR), nal_ref_idc: 3
[swscaler @ 0x7f38700e5a00] Forcing full internal H chroma due to input having non subsampled chroma
[h264 @ 0x7f3879eb2b40] Format yuv420p chosen by get_format().
[h264 @ 0x7f3879eb2b40] Reinit context to 1280x720, pix_fmt: yuv420p
[h264 @ 0x7f3879eb2b40] no picture 
[h264 @ 0x7f3879efb900] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 2
[h264 @ 0x7f3879efb900] no picture 
[h264 @ 0x7f3879f18600] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 2
[h264 @ 0x7f3879f35300] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 0
[h264 @ 0x7f3879f52000] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 0
[h264 @ 0x7f3879eb2b40] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 2
[h264 @ 0x7f3879efb900] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 2

Log File is here.

Apparently, without avcodec, the main difference is here:

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pulse debug: started
pulse debug: changing sink 0: alsa_output.pci-0000_00_1b.0.analog-stereo (Internes Audio Analog Stereo)
qt warning: qml error qrc:/widgets/DragItem.qml:52 ReferenceError: g_mainDisplay is not defined
...
qt debug: on_player_track_list_changed (audio)
pulse error: overflow, flushing
vlcpulse debug: write index corrupt

Consequently, I get

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main warning: picture is too late to be displayed (missing 4391 ms)
main warning: picture is too late to be displayed (missing 4336 ms)
main warning: picture is too late to be displayed (missing 4280 ms)
main warning: picture is too late to be displayed (missing 4224 ms)
main warning: picture is too late to be displayed (missing 4169 ms)
...

The same section with avcodec looks better:

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pulse debug: changing sink 0: alsa_output.pci-0000_00_1b.0.analog-stereo (Internes Audio Analog Stereo)
pulse debug: started
...
qt debug: on_player_track_list_changed (audio)
main debug: looking for extension module matching "any": 1 candidates

- and there are no "picture is too late" errors.

Posted: **27 May 2021 11:25**

no file no test no fix
Problem is that the video file in question is copyright protected. I did a search for a free sample video file with the same specifications (as shown in VLC) but there, the error did not occur. Is there a way to get more comprehensive audio/video format information than the one shown in VLC's codec information window?

If you can't see the problem with other files, we also can't.

Posted: **27 May 2021 12:04**

If you can't see the problem with other files, we also can't.

Here is what mediainfo says about this file:

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General
Complete name                            : vlc_test.720p.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/avc1/mp41)
File size                                : 984 MiB
Duration                                 : 30 min 2 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 4 579 kb/s
Writing application                      : Lavf58.20.100

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                                 : 30 min 2 s
Bit rate mode                            : Constant
Bit rate                                 : 3 933 kb/s
Nominal bit rate                         : 6 000 kb/s
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Variable
Frame rate                               : 23.976 (24000/1001) FPS
Minimum frame rate                       : 23.810 FPS
Maximum frame rate                       : 24.390 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.178
Stream size                              : 845 MiB (86%)
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 30 min 2 s
Duration_LastFrame                       : -5 ms
Bit rate mode                            : Constant
Bit rate                                 : 639 kb/s
Channel(s)                               : 6 channels
Channel layout                           : L R C Cb Lb Rb
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 137 MiB (14%)
Language                                 : English
Default                                  : Yes
Alternate group                          : 1

Text
ID                                       : 3
Format                                   : Timed Text
Muxing mode                              : sbtl
Codec ID                                 : tx3g
Duration                                 : 29 min 54 s
Bit rate mode                            : Variable
Bit rate                                 : 93 b/s
Stream size                              : 20.3 KiB (0%)
Title                                    : English (CC)
Language                                 : English
Default                                  : Yes
Forced                                   : No
Alternate group                          : 3

Posted: **27 May 2021 13:05**

No sample, no bug. We can't do magic.

Posted: **27 May 2021 13:40**

No sample, no bug. We can't do magic.

I understand. But I do not want to post a link to this file publicly here in the forum. Is there another way to send the sample to you?

Posted: **27 May 2021 14:49**

http://streams.videolan.org/upload/

Posted: **28 May 2021 14:27**

http://streams.videolan.org/upload/

File uploaded. Thanks a bunch for providing this opportunity.

The VideoLAN Forums

No audio with MP4 video files using mp4a at 48 kHz sample rate

No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate

Re: No audio with MP4 video files using mp4a at 48 kHz sample rate