Hi,
Why couldn't someone make a DIY audio receiver? Licenses,etc aside (not talking about the legal battle part).
Get the HDMI bit stream via some sort of capture card, decode the bitstream, tons of kodi / ffmpeg code already exists to do this, in pre, then virtualize the objects in as many channels/speakers as you desire, hook up a whole wack of cost effective usb soundcards to DAC it out to external amps. Heck 24.2.10. An RPi4 could easily handle this. Isn't hdmi 2.1 audio max 31Mbit/s? That's nothing for a multi-core arm processor with neon to handle for receiver duties.
I mean anyone could easily do all the software, it would be a weekend project to slap together a bunch of open source stuff and do some digital dsp. Just need to get the bit stream via HDMI, there are already those splitters which do the edid/content protection bit and extract the audio stream.
Is there any HDMI->usb capture card that will get the raw audio bitstream coming in? Does anyone know of any?
Why couldn't someone make a DIY audio receiver? Licenses,etc aside (not talking about the legal battle part).
Get the HDMI bit stream via some sort of capture card, decode the bitstream, tons of kodi / ffmpeg code already exists to do this, in pre, then virtualize the objects in as many channels/speakers as you desire, hook up a whole wack of cost effective usb soundcards to DAC it out to external amps. Heck 24.2.10. An RPi4 could easily handle this. Isn't hdmi 2.1 audio max 31Mbit/s? That's nothing for a multi-core arm processor with neon to handle for receiver duties.
I mean anyone could easily do all the software, it would be a weekend project to slap together a bunch of open source stuff and do some digital dsp. Just need to get the bit stream via HDMI, there are already those splitters which do the edid/content protection bit and extract the audio stream.
Is there any HDMI->usb capture card that will get the raw audio bitstream coming in? Does anyone know of any?
Ive never seen It done if you could just get digital out of a player to feed separate DACs then feed into a good legacy processor, amazing
HDMI is terrible, I have yet to better analogue out for audio in multichannel, this why I'm modding my Panasonic 9000 and sold my Acurus ACT4
HDMI is terrible, I have yet to better analogue out for audio in multichannel, this why I'm modding my Panasonic 9000 and sold my Acurus ACT4
Yeah, if anyone knows how to get in the HDMI bitstream, I'd be happy to look at digital audio processing in the pre stage with open source software, then figure out a way to feed it in whatever DACs anyone wants.
Does anyone have any ideas how to capture HDMI input -> audio bitstream? I want it raw, no processing/decoding. I want to decode it myself. Then we can do all the spatial mapping to whatever speaker assignment there is, its probably simple 3d transform, a few 4x4 matrix multiplications for this object oriented sound, I'll read the dolby specs later.
Meridian did sell a HD621 and can unpack HDMI, this unit had 8 channels out, not sure how DANTE works either as this is digitally transferred but possibly post process just pre D>A
https://www.meridian-audio.com/media/10879/hd621-hdmi-audio-processor-user-guide.pdf
https://www.meridian-audio.com/media/10879/hd621-hdmi-audio-processor-user-guide.pdf
Are you folks sure you know what you are trying to do ?
What on earth is any legacy processor going to do with 30 odd channels of ATMOS data, whatever the domain?
What on earth is any legacy processor going to do with 30 odd channels of ATMOS data, whatever the domain?
I definitely wouldn’t recommend going over 12 channels, personally I’m happy with 8 channels, I’m running 7.3.0 and EQ the subs separately. Unless of course your in a room with more than 5-6m square
Unless you are going to locate excellent ceiling speakers what you gain on positioning and effects on some films then it’s just not worth it. I counted my BR and 4K film collection and about 5% of these at Atmos or have a channel count beyond 8
I think you will need to think about either using a multichannel processor and modify the output just for digital to add external DACs, eg Storm and a few others BUT you are then stuck with a SPMS driven unit of great complexity and being fed by HDMI. I went to see all the Hugh end processors in their native territory the Trinnov was 32 running 23 channels and all had degree s of being impressed by the spatial positioning and all sounded average at best on 2 channel.
If you want high end and a 30 channel count then you need very, very deep pockets be prepared for disappointment.
Depends on your budget I guess.
Unless you are going to locate excellent ceiling speakers what you gain on positioning and effects on some films then it’s just not worth it. I counted my BR and 4K film collection and about 5% of these at Atmos or have a channel count beyond 8
I think you will need to think about either using a multichannel processor and modify the output just for digital to add external DACs, eg Storm and a few others BUT you are then stuck with a SPMS driven unit of great complexity and being fed by HDMI. I went to see all the Hugh end processors in their native territory the Trinnov was 32 running 23 channels and all had degree s of being impressed by the spatial positioning and all sounded average at best on 2 channel.
If you want high end and a 30 channel count then you need very, very deep pockets be prepared for disappointment.
Depends on your budget I guess.
PS, I spend 6 months with my Acurus ACT4 and used some of the channels for bi-amping and ultimately my Naim AV2 fed by my Panasonic 9000 player was more enjoyable, this uses a separate pre amp and power supply for L,R and I traded a bit of accuracy and precision with spatial positioning for body, dynamics and real poise and musicality with the very old naim
as an author of RPI dual audio output support in KODI (formerly XBMC), as an author of failed first attempt for OMX ALSA USB output adapter for RPI and KODI, as participant in audio upscaling project in KODI, as an author and/or participant in many other development tasks in KODI, with very limited low level knowledge of ATMOS and DTS-HD (but enough on technology in general), the only thing i can say is: you have absolutely no idea what you are talking about!
except that, good luck! some have to be the first one.
except that, good luck! some have to be the first one.
Fortunately, you have much better understandings on the topic and you already spotted what can be wrong. I, from other side, have real inside experience as developer on mentioned projects.
Didn't looked at those projects for long time, probably they still miss basic room equalization. Here mega-multi channel spatial sound decoding (from HDMI signal!) is going, with corresponding and mandatory distance/reflection/attenuation, ..... equalizations. On elementary "multi-core arm processor with neon", with "a bunch of open source stuff" and "cost effective" thingies.
Simply there is no free lunch. Only dreams are free.
I think the only polite response to the original post is simply that pull requests would be welcome anywhere in the software stack for this task. I hope you’ve got a spare weekend.
Im a professional software developer for a big high tech semi in the firmware, linux kernel dev, up to hlos arena, i do know what im talking about in terms of scope. Ive used libavcodec and openal in the past too and decoding audio is fairly straight forward. Ive seen room eq etc are done by equalizer apo, and can look at that project to see what can be ported to linux. My gut instinct says this can be done.
Anyways, before all of this is a moot point, does anyone know how to get an hdmi audio bitstream captured? I want the raw bitstream. The capture cards seem to suggest they decode and dolby/dts bitstream and give lpcm in 2/5 channel. Has anyone been able to extract raw audio bitstream data from hdmi from a capture card?
Anyways, before all of this is a moot point, does anyone know how to get an hdmi audio bitstream captured? I want the raw bitstream. The capture cards seem to suggest they decode and dolby/dts bitstream and give lpcm in 2/5 channel. Has anyone been able to extract raw audio bitstream data from hdmi from a capture card?
Great that you are so smart developer. Both KODI and ffmpeg, and others also, will be more than happy to accept your contributions of any kind. That is how those projects grow.
Why you didn't start with processing at the same host? Trust or not, capturing and providing raw audio stream from HDMI to third party is serious licensing flaw and no one will do it. As professional developer, you should be aware how serious those things are handled. On local host you have more chances to get it somehow (even by reading freed but not overwritten buffers). Probably no one of above projects will accept such contribution, but still why not to try.
Again, there always some must be the first one. Good luck.
Why you didn't start with processing at the same host? Trust or not, capturing and providing raw audio stream from HDMI to third party is serious licensing flaw and no one will do it. As professional developer, you should be aware how serious those things are handled. On local host you have more chances to get it somehow (even by reading freed but not overwritten buffers). Probably no one of above projects will accept such contribution, but still why not to try.
Again, there always some must be the first one. Good luck.
If i had infinite time id play more, but i dont. Kodi already transcodes multi channel audio from dolby or dts to lpcm, so i know it can be done. Adding atmos processing of the extra meta data seems straight forward, especially since dolby publishes the spec.
But again, i am not going to waste my time if i cant get a cheap and easy way to get the raw audio bitstream. If some cheapo capture card can do this already i might invest my time. I could spend endless hours, use an fpga, read the hdmi clocks, get the data myself but i rather not, id just buy the expensive receiver than waste months of spare time. Most of the hard work is already done by folks like you.
So has anyone gotten the raw audio bitstream from some hdmi capture card? If so, which card, what linux drivers etc?
But again, i am not going to waste my time if i cant get a cheap and easy way to get the raw audio bitstream. If some cheapo capture card can do this already i might invest my time. I could spend endless hours, use an fpga, read the hdmi clocks, get the data myself but i rather not, id just buy the expensive receiver than waste months of spare time. Most of the hard work is already done by folks like you.
So has anyone gotten the raw audio bitstream from some hdmi capture card? If so, which card, what linux drivers etc?