Audio passthrough testing

  • Hi !

    I did tests with my Oprange pi PC, I have a AVR Denon AVR-S730 and passthrough work not too bad at all


    Dolby Digital : OK

    Dolby Digital Plus : OK

    DTS : OK

    DTS-Hd : OK but a lot of clipping (cracking/popping, I don't know the good word in english, this append also with H6)

    TRUE-HD : not tested


    A really weird bug : If a disable AC3 transcoding, I set the number of channel to 7.1 and I watch an episode or a movie in AAC 5.1, I hear only the background music, no dialog... But if I set number of channel to 2.0 and I enable AC3 transcoding everything is fine.


    Another thing, with the "not passthrough release" I have a lot of sound cut, it's totally random it's really disturbating but with the passthrough relesase I have no sound cut.


    So personnally, passthrough edition is my favorite release, I disable DTS-HD and TRUE-HD passthrough, I enable AC3 transcoding and everything work pretty well.

    Libreelec : Raspberry 4, Orange pi lite2, Orange pi PC(and +), Pine H64, Rock64, RockPro64, soon Orange Pi 3 and PC2

    Divers : NVidia Shield Pro, NVidia Shield Tube, N2 and C4

    Edited once, last by mike2002 ().

  • Sorry, but it's impossible to debug something that works for me. I tested this on LG B8 TV, which supports most of compressed formats. AVRs are known to cause issues, but I have none.

    Thanks for your great work. It seems to be some race condition, considering that it works on another Opi PC, maybe it works in a future version again, as it did in the one from last September. As long as the normal version works, I am happy 😊

    • Official Post

    It seems to be some race condition, considering that it works on another Opi PC

    I don't think it's issue with board - there is no real difference regarding HDMI audio, I think it's end equipment. Just for that reason, I sometimes test with different monitors and TVs. This allowed me to fix most bugs, but obviously I don't have all quirky monitors/TV... Do you have a possibility to test passtrough on some TV which supports compressed formats directly, without AVR?

    • Official Post

    A really weird bug : If a disable AC3 transcoding, I set the number of channel to 7.1 and I watch an episode or a movie in AAC 5.1, I hear only the background music, no dialog... But if I set number of channel to 2.0 and I enable AC3 transcoding everything is fine.

    After recent investigation, I found out that this makes perfect sense. ALSA config is written in such way, that all audio is transcoded in IE958 format. This is a bit problematic - DW-HDMI IEC958 support is meant only for compressed formats, 2 ch for normal compressed streams, 8 ch for HBR. It's unclear at this point if any other channel combination may work with IEC958 format. With AC3 transcoding you make sure that there is no uncompressed audio, so IEC958 should work fine in all cases. GUI uses stereo sound, which should work with IEC958 too.

  • I've tried out devel-20210426184100-eeb359a on Orange Pi One Plus, with a Marantz NR1605. AVR is configured for 5.1 speakers but will downmix from 7.1. I've locked the gui to 1080p @60 and disabled refresh rate switching.


    *Passthrough of at least Dolby Digital (5.1 and 4.1, using the movie app), DTS 5.1 (including from a DTS audio cd rip using the music app and also movie audio using the movie app), and DTS-MA (bluray rip using the movie app, 5.1 and 7.1) works fine.


    * With the primary audio output set to allwinner-hdmi-MJI marantz-AVR any multichannel FLAC gets downmixed to stereo, and plays fine (including 96kHz, which does play at 96kHz).


    * With the audio output set to allwinner-hdmi-5091000.i2s-i2s-hifi, multichannel FLAC 96kHz is full of distortion, and stereo flac just gives silence. At least the multichannel flac is showing up as multichannel on the amp though.


    * CEC doesn't seem to work very often, but does occasionally. I get lots of 'dw_hdmi_cec_hardirq: stat=11 LOW_DRIVE' in dmesg. And occasionally 'cec-dw_hdmi: message 20 04 timed out'


    * Also, I sometimes when I turn the TV off, it turns straight back on again, which suggests the device is frequently sending "TV on" CEC messages?


    I do have a raspberry pi B+ connected to the AVR as well, which I may be able to use to watch events on the CEC bus, so I'll try and find time to give that a go over the weekend.


    Happy to test out anything else. (The AVR is too old for Atmos etc).


    Cheers


    David

  • Hi, I have updated to 9.95.3 and I still have the problem with audio channels.

    The channels are wrong forwarded to my DENON AVR 3500.


    Instead of FHL - FHR are send to denon on SBR and SBL. Someone could check it please? Thanks


    I configured kodi audio as 5.1 with passtrhough enabled.



  • Hi jernej ,

    I have pine A64 plus (2GB RAM) board. I don't see passthrough test build for this model.

    Is it possible to create one. I am happy to test and report back on the progress.


    Thanks.

  • hi, in this version of Libreeelec all scripts are installed?¿ I try to install Rpi VNC server on Libreelec-->services-->_Rpi VNC server and and show this message 'install failed".. Any addon of libreelec show me the same message "failed"


    thanks

  • First of all, this is not RPi, so nothing RPi specific will work. Second of all, VNC is not supported due to nature of display stack. However, it might get supported in future Kodi versions.

  • First of all, thank you for all the great work. All of us who want to have audio passthrough, so our highly paid HiFi equipment is put to work, are having problems finding devices that actually do that. After so many headache with Plex and different versions of OSs (basically, only bulletproof solution was HTPC with Windows or Linux, which adds to cost) I've finally stumbled on your solutions.

    I have Yamaha RX-V4A with 5.1 setup, which is connected to Philips TV. The box is Tanix TX6. Kodi reports in HDMI connection that it is connected to Philips TV HDMI, not to AVR (AVR supports Video passthrough). DTS, DD, DDP, DTS-HD MA, TrueHD work. With TrueHD I have problems that sometimes the audio cuts off, AVR reports that there is no decoder, then it comes back. That happened to me with high bitrate movies. I yet need to test with lower quality rips.

    Thank you and highly appreciated.

  • Freeman I just updated images based on latest 10.0 stable branch. I think Kodi had some TrueHD fixes, so please test if it helps.