You can now, e.g.,
```
with open("/whatever.mp3") as mp3_file:
mp3_file.seek(16000*30)
decoder.file = mp3_file
i2s.play(decoder)
```
to start about 30 seconds into a 128kbit/s CBR track.
If a track is looped, the loop will start at the beginning.
This also changes the behavior if the track is started & stopped: it will
continue from where it left off, except if it had prevously run to
completion. To get other behavior, you can seek the file and then re-assign
the file property.
This gets MP3 playback of a soma.fm stream working for up to a minute
at a time, though it's still vulnerable to network glitches.
* the buffer can empty, in which case a single block of audio
plays repeatedly in max headroom stutter fashion
* the server eventually (after 1 to 5 5 minutes) stops getting packets
at all. At this point stream playback stops, with the internal error
indicating a problem MP3 decoding (which doesn't quite make sense):
-9, ERR_MP3_INVALID_HUFFCODES.
* other combinations of audiomixer buffer & mp3 buffer might give
different results
```py
import time
import adafruit_connection_manager
import adafruit_requests
import audiobusio
import audiomixer
import audiomp3
import board
import wifi
pool = adafruit_connection_manager.get_radio_socketpool(wifi.radio)
ssl_context = adafruit_connection_manager.get_radio_ssl_context(wifi.radio)
requests = adafruit_requests.Session(pool, ssl_context)
# todo: parse PLS files like https://somafm.com/nossl/dronezone.pls
# todo: figure out why https URLs don't work at all (missing select?)
# STREAMING_URL = "http://ice2.somafm.com/dronezone-128-mp3"
STREAMING_URL = "http://ice4.somafm.com/tikitime-128-mp3"
def get_mp3_stream():
if STREAMING_URL.startswith("http:") or STREAMING_URL.startswith("https:"):
return requests.get(STREAMING_URL, headers={"connection": "close"}).socket
return open(STREAMING_URL, "rb")
mixer_buffer_size = 1152 * 2
mp3_buffer = bytearray(32768)
with audiobusio.I2SOut(
bit_clock=board.D12, word_select=board.D13, data=board.D11
) as i2s, get_mp3_stream() as stream, audiomp3.MP3Decoder(
stream, mp3_buffer
) as sample, audiomixer.Mixer(
channel_count=2, sample_rate=44100, buffer_size=mixer_buffer_size
) as m:
v = m.voice[0]
print(sample)
i2s.play(m)
v.play(sample, loop=False)
while v.playing:
time.sleep(0.1)
```
An mp3 decoder (note that this needs `audiocore.get_buffer`, not
enabled on devices):
```py
import sys
import audiomp3
import audiocore
GET_BUFFER_DONE, GET_BUFFER_MORE_DATA, GET_BUFFER_ERROR = range(3)
with audiomp3.MP3Decoder(sys.argv[1]) as decoder, open(sys.argv[2], "wb") as target:
while True:
res, samples = audiocore.get_buffer(decoder)
if res != GET_BUFFER_ERROR:
target.write(samples)
if res != GET_BUFFER_MORE_DATA:
break
```
this doesn't actually add any tests though
This can sort-of play MP3s from a http request, but the buffering is
not good enough to play glitch-free. A new kind of buffer that can
read ahead further without blocking is needed.
