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+--- Thread: No audio format on playback panel (/showthread.php?tid=6133)
RE: No audio format on playback panel - Doc77 - 01-14-2024
(01-14-2024, 01:21 AM)Tim Curtis Wrote:(01-13-2024, 10:23 PM)Doc77 Wrote:(01-13-2024, 09:49 PM)Tim Curtis Wrote: DoP is where DSD format is packed on-the-fly into PCM frames that contain a special "DoP flag" that tells the DAC to unpack the frames and send the bits to the DSD processing section on the chip.
The DoP PCM formats are:
DSD64 -> 24 bit / 176.4 kHz
DSD128 -> 24 bit / 352.8 kHz
If you see 32 bit instead of 24 bit its because the DAC only accepts 32 bit word length. In this case 24 bit is simply zero-padded to 32-bit. The original 24 bits of data are left untouched.
Exactly as you see in the attached screenshots. The only difference, as we have already said, is that by selecting Dop, I have no sound (i2s only pcm..)
But from DSD 1bit I don't get PCM 176.4 khz, but PCM 352.8 Khz?!?! The .dsf file is the same DSD 1 bit 2.822 Mhz: this is a DSD64 or DSD128 ??
Is this normal?
Many thanks @Tim Curtis
Here is the (i) help for MPD DSD support option. I've added more info below each of the options to help explain whats going on.
Native DSD: If the audio device reports that it supports Native DSD then MPD will send the unaltered DSD bitstream to the device otherwose MPD will perform DSD to PCM on-the-fly conversion.
For DSD to PCM on-the-fly conversion, the PCM rate thats sent is determined by MPD and ALSA, is a multiple of 88.2 kHz up to the max rate the audio device supports. For I2S DAC's the max rate is 384 kHz and thus DSD64 is sent at 352.8 kHz, DSD128 and above will be sent at 384 kHz. IIRC for USB DAC's that support higher PCM rates the on-the-fly rates for DSD128 and above will be higher multiples of 88.2 kHz.
DSD over PCM (DoP): There is no way to detect if an audio device supports DoP so only enable this if you are certain that the device support it otherwise the encapsulated DSD bitstream may cause loud or unpredictable distortion.
The DoP spec stipulates:
DSD64 has to be sent as 24 bit / 176.4 kHz
DSD128 has to be sent as 24 bit / 352.8 kHz
Now it's all clear! I finally understood how the process works. My Innomaker works perfectly! Thanks again for your patience and expertise! Dav
RE: No audio format on playback panel - TheOldPresbyope - 01-14-2024
@Doc77
First, this thread has stretched to 40+ posts and long since is not about the subject line. It's long since time to close it and open another if necessary with a relevant subject line.
Second...ah, well, I see Tim beat me to the punch while I was composing. In essence, you must be careful talking about those sample sizes (1-bit vs 24-bit vs 32-bit) and apparent frequencies (176.4kHz vs 352.8kHz). DSD and PCM audio are different beasts. Google is your friend if you want to do some homework on what DSD encoding (DSD64, DSD128, DSD256, and DSD512) is and how DSD-encoded material can be contained in a .dsf or .dff file. Study as well how DSD-encoding compares to PCM-encoding. Finally, study how a DSD-encoded stream can be encapsulated in PCM frames in order to slip it through PCM-only interfaces to DAC chips which know how to extract the DSD-encoded stream.
Third, I just tried sending a DSD64 track to my Tone1 with MPD set to use Native DSD format then tried sending that same track with MPD set to embed DSD as DoP. I don't want to add screen captures here so I'll give you the screen scrapes instead.
First, as native DSD
Code:
INPUT / OUTPUT
Source NAS/OMV-Music/DSD/NDSD012/10_Welcome-to-NativeDSD-Sampler_NativeDSD-Presents_NDSD012_2ch64.dsf
Source format DSD 1 bit 2.822 MHz, Stereo
Decoded to DSD 1 bit 2.822 MHz, Stereo, 5.645 Mbps
Output format DSD 1 bit 2.822 MHz, Stereo, 5.645 Mbps
ALSA mode Direct (hw)
Audio chain MPD -> hw -> DeviceDSP OPERATIONS
Resample rate Off
Quality Off
Selective Off
CamillaDSP Off
Volume type Hardware (On-chip)AUDIO DEVICE
Device Tone1
Mixer name Tone1
Interface USB
Formats S32_LE, SPECIAL, DSD_U32_BE
Platform Pi-4B 1.1 2GNote that "1-bit 2.822 MHz" is per channel. That MHz really ought to be MSs for mega-samples per second but that's the quirks of the audio world for you. Stereo is two channels so the total transmission rate is 5.645 Mbps. (mega-bits per sec).
Now again, with MPD set to embed DSD in PCM frames
Code:
INPUT / OUTPUT
Source NAS/OMV-Music/DSD/NDSD012/10_Welcome-to-NativeDSD-Sampler_NativeDSD-Presents_NDSD012_2ch64.dsf
Source format DSD 1 bit 2.822 MHz, Stereo
Decoded to DoP 24 bit 176.4 kHz, Stereo, 8.467 Mbps
Output format PCM 32 bit 176.4 kHz, Stereo, 11.290 Mbps
ALSA mode Direct (hw)
Audio chain MPD -> hw -> DeviceDSP OPERATIONS
Resample rate Off
Quality Off
Selective Off
CamillaDSP Off
Volume type Hardware (On-chip)AUDIO DEVICE
Device Tone1
Mixer name Tone1
Interface USB
Formats S32_LE, SPECIAL, DSD_U32_BE
Platform Pi-4B 1.1 2GBAh, now some interesting things happen. The 24 bit you see in "Decoded to" has been padded to "32 bit" in "Output format" because the DAC has reported it accepts only 32-bit formats. The total "Decoded to" bit rate and the total "Output format" bit rate have stretched by the same ratio simply because there are now more bits per second, albeit 1/3 1/4 of them now are zero.
Either way, the track plays fine on my system and I hear it fine. Mind you, my DAC does not support Hardware Volume control of DSD material so I have to set volume = 100 percent and use a downstream preamp to control the volume.
In your most recent reply, the first screen capture suggests that, for whatever settings you have in this case, MPD is not sending unaltered DSD material to the DAC. Rather, it is converting it on-the-fly to PCM just as described in the information provided on the MPD settings screen for DSD format, which Tim included in his reply. THIS IS NOT THE SAME AS DoP.
By the way, I have DSD-encoded material on hand only for testing purposes. Even if I thought there were an inherent advantage to this distribution mechanism, which I don't, my ears are long past their prime and I can't hear any advantage.
ETA - Oh, jeez. I see you slipped in a final reply while I was wordsmithing. Looks like we're done here.
Regards,
Kent