Dear List,
I'm just creating a little application for my openmoko freerunner,
unfortunately in python, so that I have to use pyogg and
pyvorbis(http://ekyo.nerim.net/software/pyogg/index.html) as wrappers
around the C-functions and objects.
I've got it all installed, after applying some patches and trying to run
an example of encoding a wave-file I just get an empty ogg-file, the
right header and so on, but no data has been written.
The python-example is the following:
_____________________________
#!/usr/bin/env python
'''An example of encoding using the Python wave
module'''
import ogg.vorbis, wave
fout = open('out.ogg', 'wb')
inwav = wave.open('in.wav','rb')
channels = inwav.getnchannels()
vd = ogg.vorbis.VorbisInfo(channels = channels,
rate = inwav.getframerate(),
quality = 0.2).analysis_init()
os = ogg.OggStreamState(5)
map(os.packetin, vd.headerout())
og = os.flush()
while og:
og.writeout(fout)
og = os.flush()
nsamples = 1024
eos = 0
total = 0
while not eos:
data = inwav.readframes(nsamples)
total = total + nsamples
if not data:
vd.write(None)
break
vd.write_wav(data)
#print 100.0 * total / inwav.getnframes()
vb = vd.blockout()
while vb:
vb.analysis()
vb.addblock()
op = vd.bitrate_flushpacket()
while op:
os.packetin(op)
while not eos:
og = os.pageout()
if not og: break
og.writeout(fout)
eos = og.eos()
op = vd.bitrate_flushpacket()
vb = vd.blockout()
_________________________
Only knowing very few about C and just something about the vorbis-codec,
I found that the problem occurs here:
og = os.pageout()
if not og: break
no page is actually written, it returns None. And consequently it breaks.
The wrapper-source says this:
/* TODO: You can't keep a page between calls to flush or pageout!! */
static PyObject *
py_ogg_stream_pageout(PyObject *self, PyObject *args)
{
ogg_page op;
int res;
if (!PyArg_ParseTuple(args, ""))
return NULL;
res = ogg_stream_pageout(PY_OGG_STREAM(self), &op);
if (res == 0) {
Py_INCREF(Py_None);
return Py_None;
}
return py_ogg_page_from_page(&op);
}
And ogg_stream_pageout always returns 0, so, insufficent data has been
accumulated to write a page.
Can anyone help me and guess, where the fault may be. After all I've
read this seems to be the right encoding procedure. So is it the
python-wrapper? Is it the data I've been using (16Bit-Little Endian,
16000Hz, Mono wav-file) wrong?
Thank you very much!
Matthias
