Need some help or guide for using bit perfect playback

[Subhasis Das]

Hi Guys

Need some help or guide to utilise bit perfect playback via external dac and also via phone internal dac .

Thanks

[andrewilley]

Poweramp does not have a "bit perfect" mode as such. To be honest, as soon as you have an EQ available, or a digital volume control, then exactly matching the input bytes to the output bytes is an impossible task anyway. 

What some people have asked for though is an "output follows source frequency" feature, which is not something that is currently implemented in Poweramp but might be in the future if the Android device in question can support it. Currently, you need to set a maximum output sampling frequency and bitrate, and everything will be output using that setting (upscaled or downscaled as appropriate). Dynamic changing may come in the future though - although if enabled it will break a number of existing features such as crossfade, gapless, etc.

On 4/28/2022 at 11:05 AM, andrewilley said:

• 'No Resample' mode (sometimes misnamed as "bit perfect") where the output is adjusted automatically to match each source file's frequency. [ LINK1  LINK2  LINK3 ]

Andre

[Subhasis Das]

23 hours ago, andrewilley said:

Poweramp does not have a "bit perfect" mode as such. To be honest, as soon as you have an EQ available, or a digital volume control, then exactly matching the input bytes to the output bytes is an impossible task anyway. 

What some people have asked for though is an "output follows source frequency" feature, which is not something that is currently implemented in Poweramp but might be in the future if the Android device in question can support it. Currently, you need to set a maximum output sampling frequency and bitrate, and everything will be output using that setting (upscaled or downscaled as appropriate). Dynamic changing may come in the future though - although if enabled it will break a number of existing features such as crossfade, gapless, etc.

Andre

Thanks for the reply , in such situation , is there a way of direct android audio bypass , so that i can utilize my chord mojo dac which is connected to a LG V60 . I mean to say how am i suppose to bypass the android audio playback limitations while utilizing the full potential of my dac which has 32bit at 768khz playback capabilities . 

Thanks

[andrewilley]

@Subhasis Das In Poweramp, you can't. It uses Android's low-level audio processing paths rather than including any dedicated code to drive specific hardware at crazy sampling rates.

Andre

[MotleyG]

1 hour ago, Subhasis Das said:

Thanks for the reply , in such situation , is there a way of direct android audio bypass , so that i can utilize my chord mojo dac which is connected to a LG V60 . I mean to say how am i suppose to bypass the android audio playback limitations while utilizing the full potential of my dac which has 32bit at 768khz playback capabilities . 

@Subhasis Das Best case is to make some manual settings to achieve "Bit Perfect" output from Poweramp.

Assuming your Chord Mojo, or some amplifier component beyond, has some sort of volume control, and you are connected with the appropriate USB OTG connector to allow this to work;

1. Disable all of you audio processing in Poweramp. Go to the EQ tab at the bottom, defeat the EQ, Tone, and Limitier buttons. Also check to make sure the Tempo and Mono effects ared disabled, as well as all of the Reverb features in the other tabs at the top. You may also need to check the audio settings in your phone to ensure these are also disabled. Settings>Audio>Crossfade, Fade, and Gapless all settings need to be set to No fading. Settings>Audio>Replaygain also needs to be disabled. There can be no DSP in order to maintain "bit perfect" output.

2. With the USB device connected, turn up the volume control to 100%. This ensures there is no digital signal reduction affecting the original details. There can be no DSP (including volume attenuation) in order to maintain "bit perfect" output.

3. Go to Settings>Audio>Output>Hi-Res Output>USB DAC (make sure this one is enabled)then set your Sample Rate and Sample Format to match the file(s) you are going to play. Note that this setting is not capable of "following" your source, so if you want it to match exactly what your files are using, you may need to change these 2 settings each time you change tracks. Otherwise Poweramp will resample the files internally to match what is selected, and you no longer will have a "bit perfect" stream.  There can be no DSP in order to maintain "Bit Perfect" output.

4. Press play and enjoy your music.

 

If what you actually want is "Follow Source Fequency" and not "bit perfect" you can ignore steps 1. and 2. At step 3. you would still need to adjust the Sample Rate and Sample Format manually. Now Poweramp will keep your files in the original bit rate and depth, but allow you to make changes to the tuning, including any volume control.

 

Hopefully either or both of these functions can be built into a specific DAC selection mode in Poweramp at some point. The "Follow Source Frequency" option would simply disable all tone functions at one time. The "Bit Perfect" mode would probably need some disclaimer to be accepted first, as this forces a full volume output that may have consequences if applied without a true external DAC with volume capabilities. And in both cases, the USB DAC output mode would need a new option to use the sample rate and sample rate format of the file rather than being defined by the device, or manually selected. For now, this is as close as I can make it with my outboard DAC setup.