Stuttering with audio passthrough

Dev Community Apps & Creations
1

Hi folks,

 

I have audio issues with some of my mkv files and hope you can help me.

Even if I play for example my biggest mkv file the playback stuttering terrible (3-4 times per second) and I can see the Dolby logo flicker at my AVR.

BUT I find out that I can watch this film perfectly if I disable the “ac3 passthrough” in my settings.

So I think it is no buffer problem.

I have enable and disable FFMPEG AVIO but it makes no different.

 

My setup is:

Pi 2 with 0.5.1 ---HDMI---> AVR ---HDMI--->TV

The Pi is wired connected

 

What could be my problem?

 

Here the Media- Info:

 

 

Format                                   : Matroska

Format version                           : Version 2

File size                                : 31,2 GiB

Duration                                 : 2h 34min

Overall bit rate                         : 28,9 Mbps

 

Video

ID                                       : 1

Format                                   : AVC

Format/Info                              : Advanced Video Codec

Format profile                           : High@L4.1

Format settings, CABAC                   : Ja

Format settings, ReFrames                : 4 frames

Codec ID                                 : V_MPEG4/ISO/AVC

Duration                                 : 2h 34min

Bit rate                                 : 27,7 Mbps

Width                                    : 1 920 Pixel

Height                                   : 1 036 Pixel

Display aspect ratio                     : 1,85:1

Frame rate mode                          : konstant

Frame rate                               : 23,976 FPS

Color space                              : YUV

Chroma subsampling                       : 4:2:0

Bit depth                                : 8 bits

Scan type                                : progressiv

Bits/(Pixel*Frame)                       : 0.581

Stream size                              : 29,9 GiB (96%)

Writing library                          : x264 core 130 r2273 b3065e6

Language                                 : Englisch

Default                                  : Ja

Forced                                   : Nein

Color primaries                          : BT.709

Transfer characteristics                 : BT.709

Matrix coefficients                      : BT.709

Color range                              : Limited

 

Audio

ID                                       : 2

Format                                   : AC-3

Format/Info                              : Audio Coding 3

Mode extension                           : CM (complete main)

Format settings, Endianness              : Big

Codec ID                                 : A_AC3

Duration                                 : 2h 34min

Bit rate mode                            : konstant

Bit rate                                 : 640 Kbps

Channel(s)                               : 6 Kanäle

Channel positions                        : Front: L C R, Side: L R, LFE

Sampling rate                            : 48,0 KHz

Bit depth                                : 16 bits

Stream size                              : 707 MiB (2%)

Language                                 : Deutsch

Default                                  : Ja

Forced                                   : Nein

2

I have the same problem with high bitrate mp4 files with AC3 audio. The movie plays fine but the audio cuts in and out and the Dolby Digital light on my receiver flickers. It only happens with high bitrate videos though ( >20mbps). I've been talking to another user that has the same problem but we have been unable to track down exactly what causes the issue. The strange thing is that a high bitrate video with a DTS track plays fine. 

3

I have got exactly the same. I have this problem only with high bitrate files, too. Everything is fine if I disable the ac3 passtrough but so I got only 2.0. I can`t test files with a dts track because I haven`t. The most of my files I have convert with ac3 because the most devices support ac3.

4

I to have been working on this problem and can add some additional information.

I'm running RP2 and a overclocked RP B with the latest RasPlex loaded via clean installs.

I am testing on a Yamaha RX-V475 and a Denon 4806CI receiver. The media all comes via the latest PlexPass PMS running on a i7 based 2012 R2 server with other clients as well.

Just about all my movies are using the AC3 or DTS codecs and I use audio pass-through for this.

With Avatar (1080P) and the DTS track all is fine. If I select the AC3 6ch 448kbps, the audio stutters and the AVR's DD light flickers on and off.

With other movies with AC3 6ch and 640kbps the stuttering is worse occurs like CatchBo every 3 to 4 seconds. Movies such as Lord of the Rings - Return of the King or Dark Knight.

This occurs with either RPi and on either AVR. Normally I use a Mac Mini with PHT on the Denon and all work fine.

As a test I created a SD card with KODI and tested it with the RPi 2 in the same environment and no stuttering when using a SMB share. After installing PleXBMC I could still play the same movies with pass-through no problem via PMS.

As rcork has seen, high bitrate video with DTS at 1.5Mbps works fine, yet 1080P with AC3 6ch at 448kbps or 640kbps stutter only the audio, Video is rock solid, and the DD light flickers on either AVR. The only way I can use RasPlex with the 1080P movies is to disable Audio Passthrough, then all is well.

RasPlex is awesome and with teh new RPi 2 is it very responsive in the menus. Far superior to Roku 2 and Roku 3 which I have given up on with Plex due to inability to support any higher bitrate video with Direct Play.

5

I to have been working on this problem and can add some additional information.
 
I'm running RP2 and a overclocked RP B with the latest RasPlex loaded via clean installs.
I am testing on a Yamaha RX-V475 and a Denon 4806CI receiver. The media all comes via the latest PlexPass PMS running on a i7 based 2012 R2 server with other clients as well.
Just about all my movies are using the AC3 or DTS codecs and I use audio pass-through for this.
With Avatar (1080P) and the DTS track all is fine. If I select the AC3 6ch 448kbps, the audio stutters and the AVR's DD light flickers on and off.
With other movies with AC3 6ch and 640kbps the stuttering is worse occurs like CatchBo every 3 to 4 seconds. Movies such as Lord of the Rings - Return of the King or Dark Knight.
 
This occurs with either RPi and on either AVR. Normally I use a Mac Mini with PHT on the Denon and all work fine.
 
As a test I created a SD card with KODI and tested it with the RPi 2 in the same environment and no stuttering when using a SMB share. After installing PleXBMC I could still play the same movies with pass-through no problem via PMS.
 
As rcork has seen, high bitrate video with DTS at 1.5Mbps works fine, yet 1080P with AC3 6ch at 448kbps or 640kbps stutter only the audio, Video is rock solid, and the DD light flickers on either AVR. The only way I can use RasPlex with the 1080P movies is to disable Audio Passthrough, then all is well.
 
RasPlex is awesome and with teh new RPi 2 is it very responsive in the menus. Far superior to Roku 2 and Roku 3 which I have given up on with Plex due to inability to support any higher bitrate video with Direct Play.


There is a known issue with 0.5.0 and 0.5.1 due to FFMEG AVIO and transcoding, neither of which are perfect in those releases. Initial tests of the new code for the next release have been positive and this issue will hopefully be resolved in the next release.
6

There is a known issue with 0.5.0 and 0.5.1 due to FFMEG AVIO and transcoding, neither of which are perfect in those releases. Initial tests of the new code for the next release have been positive and this issue will hopefully be resolved in the next release.

Ned, all my files direct play. Nothing is being transcoded so does FFMPEGAVIO really come into play here?

7

Ned, all my files direct play. Nothing is being transcoded so does FFMPEGAVIO really come into play here?


Yes and no, it's all connected with the ability to play high bitrate media, FFMPEG AVIO was introduced some time ago to enable playing of media with bitrates up to 20Mbit, media above 20Mbit was then transcoded, however, any multi channel audio would still be passed through to a suitably capable amp. Something went wrong in 0.5.0 and then subsequently 0.5.1 which causes the issues that a number of people are now experiencing, AVIO became broken. The next release will correct that code and include new patches to the player to rectify this. The next release is in early test stages but very high bitrate media has been played with none of the issues you outline.

Regards
8

Yes and no, it's all connected with the ability to play high bitrate media, FFMPEG AVIO was introduced some time ago to enable playing of media with bitrates up to 20Mbit, media above 20Mbit was then transcoded, however, any multi channel audio would still be passed through to a suitably capable amp. Something went wrong in 0.5.0 and then subsequently 0.5.1 which causes the issues that a number of people are now experiencing, AVIO became broken. The next release will correct that code and include new patches to the player to rectify this. The next release is in early test stages but very high bitrate media has been played with none of the issues you outline.

Regards

Thanks for the clarification Ned. If you need any alpha/beta testers, i have a B+ and RPi2 model and would be willing to put it through it's paces.

9

Okay, thank you Ned for your response. So we have to wait for the next release and see what happen.

10

Glad this is a bug and not a limitation of RP2. :)

I hit the same issue on mpeg2 files from OTA recordings (1080i/720p). Being my first Pi I wasn't sure if this is a limitation of the pi hardware as nothing I do seems to help and I don't have any other Pi to compare.

Last night I tested with OpenElec as DLNA client talking to PMS and it played back fine! Then I know it's a bug in RasPlex.

Hope this gets fixed soon! Thank you!

Also, does anyone know if the older B+ model is capable of playing back these files that people are having trouble with?

11

Glad this is a bug and not a limitation of RP2. :)
 
I hit the same issue on mpeg2 files from OTA recordings (1080i/720p). Being my first Pi I wasn't sure if this is a limitation of the pi hardware as nothing I do seems to help and I don't have any other Pi to compare.
 
Last night I tested with OpenElec as DLNA client talking to PMS and it played back fine! Then I know it's a bug in RasPlex.
 
Hope this gets fixed soon! Thank you!
 
Also, does anyone know if the older B+ model is capable of playing back these files that people are having trouble with?


You need a licence from RaspberryPi.org to direct play MPEG2 media
12

I use the RPi B and RP 2 with OTA from an HDHR with no trouble, however I do have the MPEG2 license installed as Ned mentions, so it direct plays no problem.

13

You need a licence from RaspberryPi.org to direct play MPEG2 media

Yes I did buy the license and was having trouble, making me feel like I wasted the money. :) Now that I know it'll work, I feel better. ;)

14

I am having the same issue with AC3 coded blu-ray files (mkv wrapper). Using 0.5.1 and RPI2.  The video and audio stutters when set to AC3 passthrough (reciever front lights show coming and going in line with the stutters).  But DTS files play fine.  EAC3 files are transcoded -- and end up as PCM 2.0 -- and they play fine.

I have both VC1 and MPEG2 licenses.  Receiver is Denon 4520.