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Toggle playback sample rate iriver H100 H300?

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Julian67:
I noticed that on my Clip+ current git versions of Rockbox allow me to toggle the playback sample rate between 44100 and 48000 Hz so avoiding using a sample rate converter.   The hardware in my iRiver H140 and H340 also supports 48000 Hz sample rate and the original firmware apparently plays either 44100 or 48000 without rate conversion.  Is the ability to toggle the supported playback sample rate coming to the iRiver port?

saratoga:
The H100/H300 doesn't support 48k as far as I know, so that option isn't possible.

Julian67:
The hardware datasheet for the Philips UDA1380 states:


--- Quote ---Supports sample frequencies from 8 to 55 kHz for the
ADC part, and 8 to 100 kHz for the DAC part. The ADC
does not support DVD audio (96 kHz audio), only
Mini-Disc (MD), Compact-Disc (CD) and Moving Picture
Experts Group Layer-3 Audio (MP3). For playback
8 to 100 kHz is specified. DVD playback is supported.
--- End quote ---

In fact the datasheet offers most of its specs for 48 KHz audio.  My H140 no longer has iRiver firmware but I have the manual in pdf form.  It contains the following:

On the section on recording (page 34 of paper manual):


--- Quote ---When saving as WAV file, the Bitrate generally is 1411Kbps.
(44.1 KHz, 16Bit, Stereo)
When saving the optical signal with 48KHz as WAV file,
the Bitrate is 1536Kbps. (48 KHz, 16Bit, Stereo)
--- End quote ---

and


--- Quote ---Optical recording can sample at 44.1KHz or 48KHz.
--- End quote ---

On page 2 of the paper manual, section Unique Features:


--- Quote ---Multi-Codec Player
Supports MP3, Ogg Vorbis, WMA, ASF, and WAV formats as a multi-Codec
player.
The H140 supports WAV types of 11/22/44/48KHz, 16bit, Mono/Stereo.
--- End quote ---

So it seems the hardware does support 48000 for playback and recording.

edit: also on the H340 if I play a 48 KHz wav file in original firmware the OF's WPS displays at the bottom of the screen "codec" "rate" "bitrate", for example "WAV" "48KHz" "1536K".  Judging by my always reliable tin ear I don't believe there is any sample rate conversion, and the on screen indicators are a true indication of what is being ouput (not some trick reference to a pre-conversion state).

saratoga:
The DAC supports it but as far as I know the player does not.  Playback of 48k files is normal they're just trampled.

Julian67:

--- Quote from: saratoga on July 20, 2013, 02:29:00 AM ---The DAC supports it but as far as I know the player does not.  Playback of 48k files is normal they're just trampled.

--- End quote ---

This "trampling" doesn't seem to be the case.  I performed a practical test/demonstration to check:

I made two 10000 Hz test tones, one 44100 and the other 48000.  I chose 10000 Hz because it is very easy to hear and also because sample rate conversion of a 10000 Hz tone produces clear audible difference in pitch even with high quality resampler such as SRC best or SoX.  With medium or low quality rate conversion the differences are gross.

I used sox to make the test tones like so:


--- Code: ---sox -n -b 16 -c2 -r44100 44_10000.wav synth 30 sine 10000 dither -s

sox -n -b 16 -c2 -r48000 48_10000.wav synth 30 sine 10000 dither -s
--- End code ---

When I play the two files on my H340 with iRiver firmware each file sounds absolutely identical.  The only way to detect a difference is by checking the on-screen status indicators for sample rate and bit rate.

Next I boot my H340 to Rockbox daily build of July 18.

The 44100 file sounds normal (just like in iRiver firmware or like on my desktop SPDIF>receiver)  but the 48000 file's tone is completely different.

By comparison on my PC if I play the two files SPDIF>Home Theatre Receiver they sound identical.  If I use the PC's system sample rate converter (SRC at best quality, default rate 44100) there is a difference in tone.  If I set my system rate converter to linear at 44100 the 48000 file now produces a tone like the rate converter in Rockbox.

So to me it looks like:

The hardware definitely supports 48000 KHz files without rate conversion both for playback and recording.

The manufacturer states the device supports 48000 KHz files, implicitly without rate conversion for playback, explicitly so for recording.

44100 and 48000 Hz tones sound absolutely identical in iRiver H340 with iRiver firmware, which is not the case with even very high quality sample rate converters available for PC.

It's not likely that iRiver devised the world's best sample rate converter but kept silent about it, instead deciding to misreport sample rate and bit rate on the display.

Conclusion: the H340 (and implicitly the H140) does support 48000 KHz playback without sample rate conversion.

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