VS1053 MP3 play back slow and 'wobbly'

[ylh]

I have a Geeetech Arduino shield which I use with the Leonardo. I am using Adafruit's player_simple program.

I have worked through all the pinouts and settings (running at SPI_HALF_SPEED). I have made small changes in order to initialize the player correctly.

I can play an .mp3 file from the onboard SD reader (i have a high speed 4G card) but it comes out slightly slow and has this 'wobbly' sound.

I have messed with sciWrite(VS1053_REG_CLOCKF, 0xC000); using different values but I think 0xC000 is correct for the 12.288 Geeetech board.

Anything else I need to try?

Please help! Thanks.

[pasi]

Does the song play the correct amount of time? Does it otherwise sound correct, i.e. no noise or interruptions?

Check that you DO NOT set the SM_STREAM_MODE bit of the SCI_MODE register.

Are you reading or writing other SCI registers during playback?

[ylh]

Hi - it plays all the way to the end but sounds awful (and slower than it should be).

Here are the registers:
VS1053 Simple Test
Mode = 0x800
Stat = 0x48
ClkF = 0xC000
Vol. = 0x2828
Version = 4

It looks like the SM_STREAM_MODE is not set.

I have put the code here: https://github.com/ylh888/VS_player_simple

The "New recording" has a sample of the output: first from the VS1053, then from my desktop.

Thanks.

[pasi]

Hi,

What bitrate is the file you're trying to play?

Possible problems that could create that sound:
1) Too slow clock - but 0xc000 in CLOCKF should be enough (check that you don't overwrite the value and it reads back correctly)
2) Too slow data transfer - is DREQ high all the time?
3) Byte/word count mixup - you are potentially sending dummy data after each sector data? xDCS low during SD access?

[Henrik]

Hello,

have you been able to solve your issue?

Based on how your sample sounds, I think (2) is the most likely of Pasi's suggestions, possibly also (3).

I'll make some wild guesses based on this observation:
- It seems that the sound comes out in 28-30 millisecond bursts

Assumptions and guesses:
- Do you read, then send data one 512-byte disk block at a time?
- If so, a 128 kbit/s file played too slow would cause artifacts like in your file

So, if you do read/send data 512 bytes at a time, and the file you played is a 128 kbit/s CBR (constant bit-rate) MP3, I'd say Pasi's suggestion (2) is extremely likely to be your issue.

Kind regards,
- Henrik

[ylh]

Hello,

Thanks for the response.

The code seems to indicate that I read 32 bytes at a time:
#define VS1053_DATABUFFERLEN 32

Changing this to 512 does not play.

My buffer is declared in bytes and I believe the SD file read() is also in bytes.

I verified that the clock speed is at 0xC000 and that does not change through playing.

The DREQ pin is digital connected to pin 2 from the VS1053 shield and does seem to be held high at all time.

[pasi]

If DREQ is high all the time, you are not sending data quickly enough.

You can't send 512 bytes at a time (without checking the fill state of the SDI FIFO), but you can read 512 bytes from the storage, then send that 512 bytes in 32-byte blocks, checking the DREQ state before sending each 32 bytes.

[ylh]

So the symptom seems to indicate that I read too slowly to be feeding the VS1053 (hence also why the music is slow - the 'wobbly' output is just an effect).

Reading 512 bytes at a time might help but I will need to do that asynchronously to feeding the VS1053 at 32 bytes a time.

It will take me a little time to make the change.

Thanks for the insight.

[ylh]

Come to think of it: the SD library's read() is blocking. Reading 512 bytes from it each time will likely miss sending data to the VS1053.

I now wonder if there is something else other people are doing that could make this Geeetech board work.

[Henrik]

Try this:
Read 512 bytes (= one disk block) at the time from SD, then send the data in sixteen 32-byte chunks to VS1053. If that makes your SD read faster, it may solve your issue in one stroke. The VS1053 has an input buffer that is 2 kilobytes, so it can easily tolerate that you don't feed data to it all the time.

Kind regards,
- Henrik