Hello together, I hope i found the correct topic for that.
I'm currently working on my own AV-Receiver (6 channels => 5.1). In order to apply the method divide and conquer, I split the whole project into 6 subgroups, e.g. Power-Supply, Front-End, Power-Amplifiere, DAC, etc. As the PCBs for the Power-Amplifier are ordered right now and have to wait for approximately 3 weeks until they arrive, I started with the front-end in parallel.
The plan for the Front-End is to use SPDIF from my TV (and later on split the HDMI-Signals via an ADV7612 Chip). Therefore, I work on a evaluation board to get used with several Chips (CS4816, DIX4192 and the STM32H750). All of them are capable to decode AES-3, but not AC3; (I want to try different Chips to see which one works better for me). And that is the point where my struggle begins. And the question is simple, how works AES-3 and AC3 together and where is the difference to Dolby-Digital (maybe encryption?).
In order to check, whether my TV is sending something, which i can receive, i already tested a receiver and had a look on my oscilloscope, saying we have a datarate of approximately 6 MBit/s. However, as I understand it correctly, AES-3 transmitts only stereo-data divided into blocks/Subframes/Channel (A/B). Even with 24 Bit and 44KBits the 6 MBit via SPDIF is way more than AES-3 would require to transmit only stereo data (maybe I'm something missing). However, the next thing is, the manual of my TV says only 5.1 data is transmitted via SPDIF, which should be AES-3, right? As far as i understood it correctly, the AC3 data is transmitted via AES-3 but i didn't found more details on how they do that, the DIX4192 for instance is capable to detect that AC3 data is received, but once more I'm confused how AES-3/AC3 works together or how the synchronization is done to the video signal of the TV.
Furthermore, I read alot of Dolby-Digital and most of time i read that it's "only" AC3 and nothing more. Other websites say it is something complete different to each other and others are also claiming Dolby-Digital is equal to AC3 and DTS, thus I'm sitting here with a big question mark over my head 😀.
It would great if somebody can shed some light into the dark (maybe with references, so I can read more about it). Sorry for my stupid questions, right no I feel pretty dumb about it...
I'm currently working on my own AV-Receiver (6 channels => 5.1). In order to apply the method divide and conquer, I split the whole project into 6 subgroups, e.g. Power-Supply, Front-End, Power-Amplifiere, DAC, etc. As the PCBs for the Power-Amplifier are ordered right now and have to wait for approximately 3 weeks until they arrive, I started with the front-end in parallel.
The plan for the Front-End is to use SPDIF from my TV (and later on split the HDMI-Signals via an ADV7612 Chip). Therefore, I work on a evaluation board to get used with several Chips (CS4816, DIX4192 and the STM32H750). All of them are capable to decode AES-3, but not AC3; (I want to try different Chips to see which one works better for me). And that is the point where my struggle begins. And the question is simple, how works AES-3 and AC3 together and where is the difference to Dolby-Digital (maybe encryption?).
In order to check, whether my TV is sending something, which i can receive, i already tested a receiver and had a look on my oscilloscope, saying we have a datarate of approximately 6 MBit/s. However, as I understand it correctly, AES-3 transmitts only stereo-data divided into blocks/Subframes/Channel (A/B). Even with 24 Bit and 44KBits the 6 MBit via SPDIF is way more than AES-3 would require to transmit only stereo data (maybe I'm something missing). However, the next thing is, the manual of my TV says only 5.1 data is transmitted via SPDIF, which should be AES-3, right? As far as i understood it correctly, the AC3 data is transmitted via AES-3 but i didn't found more details on how they do that, the DIX4192 for instance is capable to detect that AC3 data is received, but once more I'm confused how AES-3/AC3 works together or how the synchronization is done to the video signal of the TV.
Furthermore, I read alot of Dolby-Digital and most of time i read that it's "only" AC3 and nothing more. Other websites say it is something complete different to each other and others are also claiming Dolby-Digital is equal to AC3 and DTS, thus I'm sitting here with a big question mark over my head 😀.
It would great if somebody can shed some light into the dark (maybe with references, so I can read more about it). Sorry for my stupid questions, right no I feel pretty dumb about it...
AES 3 is the transport medium. You can move two things across it. Audio data or non-audio data. Audio data is linear PCM. Non-audio data is compressed audio data like AC3 or DTS. The meta data associated with the transmitted data is transmitted as the channel status data. When moving non-audio data, a flag is set in the channel status data telling downstream equipment that the incoming data is not audio data and to treat it accordingly.
Linear PCM is easy. It is what the medium was designed to do and any digital audio interface chip datasheet will cover that. Non-audio data, OTOH, no quite so straightfoward.
This aspect is covered by a document titled IEC61937. It comes in a number parts, each covering different specifics. For instance part 3 -IEC 61937-3 is titled ( IEC60958 is what the IEC call AES3.)
DIGITAL AUDIO - INTERFACE FOR NON-LINEAR PCM ENCODED AUDIO BITSTREAMS APPLYING IEC 60958 - PART 3: NON-LINEAR PCM BITSTREAMS ACCORDING TO THE AC-3 AND ENHANCED AC-3 FORMATS.
In short it covers Dolby. Then there is one for DTS and at least two for MPEG.
Linear PCM is easy. It is what the medium was designed to do and any digital audio interface chip datasheet will cover that. Non-audio data, OTOH, no quite so straightfoward.
This aspect is covered by a document titled IEC61937. It comes in a number parts, each covering different specifics. For instance part 3 -IEC 61937-3 is titled ( IEC60958 is what the IEC call AES3.)
DIGITAL AUDIO - INTERFACE FOR NON-LINEAR PCM ENCODED AUDIO BITSTREAMS APPLYING IEC 60958 - PART 3: NON-LINEAR PCM BITSTREAMS ACCORDING TO THE AC-3 AND ENHANCED AC-3 FORMATS.
In short it covers Dolby. Then there is one for DTS and at least two for MPEG.
Hi, thank you very much for your reply - and sorry for the late answer, I appologize. However, due to my hospital stay, i was able to design at least the power supply and the amplifiers 🙂. As you can see attached. I know its not much, but however things are going steady and hoepfully, everything goes as expected 🙂 However, despite my plan, to decode 5.1 directly, i will use an intermediate step and use an 5.1 Audio-grabber to get this thing working as fast as possible 🙂
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.