使用 Python 处理 Ogg 文件

Question

我有一个“oggscissors.py”脚本，可以剪切和加入 ogg 文件。它需要 pyogg 和 pyvorbis 绑定。当我尝试执行这个脚本时，Python 解释器崩溃了。该脚本的源代码是：

import getopt
import ogg.vorbis
import sys

def usage():
    print 'usage:'
    print '  oggscissors.py --analyze file.ogg'
    print "  oggscissors.py --from=startpos --upto=endpos in.ogg out.ogg"
    sys.exit("  oggscissors.py --join in1.ogg in2.ogg out.ogg")

def analyze_packets(fin, filenamein):

    count = None
    copied = 0
    written = 0
    pageno = 0

    instream = None

    insync = ogg.OggSyncState()

    while count == None or copied < count:
        b = fin.read(65536)
        if not b:
            break
        insync.bytesin(b)

        skipped = 1
        while skipped != 0:
            skipped, page = insync.pageseek()
            print 'read', skipped, 'bytes:', page
            if skipped > 0:
                if instream and page.serialno() != serialno:
                    print 'we hit a chain boundary, leaving'
                    break
                if not instream:
                    serialno = page.serialno()
                    instream = ogg.OggStreamState(serialno)
                page.pageno = pageno
                pageno = pageno + 1
                instream.pagein(page)
                while 1:
                    p = instream.packetout()
                    if not p:
                        break
                    print '  read', p
                    copied = copied + 1
            elif skipped < 0:
                print 'skipped', -skipped, 'bytes'


def count_packets(fin):
    print 'Counting packets',

    fin.seek(0)
    count = 0
    instream = None
    insync = ogg.OggSyncState()

    while 1:
        b = fin.read(65536)
        if not b:
            break
        insync.bytesin(b)

        skipped = 1
        while skipped != 0:
            skipped, page = insync.pageseek()
            if skipped > 0:
                if instream and page.serialno() != serialno:
                    print 'we hit a chain boundary, leaving'
                    break
                if not instream:
                    serialno = page.serialno()
                    instream = ogg.OggStreamState(serialno)
                instream.pagein(page)
                while 1:
                    p = instream.packetout()
                    if not p:
                        break
                    #print '  read', p
                    count = count + 1
            elif skipped < 0:
                print 'skipped', -skipped, 'bytes'

    fin.seek(0)
    print count
    return count


def copy_packets(fin, fout, outstream=None, skip_packets=0, count=0, written_pages=0, written_packets=0, granule_delta=0, last_chunk=0):

    fin.seek(0)

    copied = 0
    written = 0
    orig_packetno = 0
    granule_skip = 0

    if last_chunk and count == 0:
        total_packets = count_packets(fin) - skip_packets

    instream = None

    insync = ogg.OggSyncState()

    if skip_packets: print 'Skipping packets', skip_packets,

    while count == 0 or copied < count:
        b = fin.read(65536)
        if not b:
            break
        insync.bytesin(b)

        skipped = 1
        while skipped != 0:
            skipped, page = insync.pageseek()
            if skipped > 0:
                if instream and page.serialno() != serialno:
                    print 'we hit a chain boundary'
                    # we hit a chain boundary
                    break
                if not instream:
                    serialno = page.serialno()
                    instream = ogg.OggStreamState(serialno)
                    if not outstream:
                        outstream = ogg.OggStreamState(serialno)
                #print 'reading', page
                instream.pagein(page)
                while count == 0 or copied < count:
                    p = instream.packetout()
                    if not p:
                        break
                    if (skip_packets > 0):
                        #print '  skipping', p, 'yet to skip:', skip_packets
                        skip_packets = skip_packets - 1
                        orig_packetno = orig_packetno + 1
                        if p.granulepos != -1:
                            granule_skip = p.granulepos
                        if skip_packets % 1000 == 0: print skip_packets,
                        if skip_packets == 1: print
                        continue
                    #print '  reading', p
                    if p.eos:
                        p.eos = 0
                    if last_chunk:
                        if count > 0:
                            if copied + 1 == count:
                                p.eos = 512
                        else:
                            if copied + 1 == total_packets:
                                p.eos = 512
                    if written_packets >= 3:
                        if samples.has_key(orig_packetno):
                            granule_delta = granule_delta + samples[orig_packetno]
                        else:
                            granule_delta = granule_delta + 1024
                            print 'Unknown size of packet', orig_packetno
                        p.granulepos = granule_delta
                    #print '  writing', p
                    outstream.packetin(p)
                    copied = copied + 1
                    written_packets = written_packets + 1
                    orig_packetno = orig_packetno + 1
                    if copied % 1000 == 0: print copied,
                    if copied % 25000 == 0:
                        print
                        written_pages, written, outstream = dump_pages(outstream, written_pages, written)
            elif skipped < 0:
                print 'skipped', -skipped, 'bytes'

    print copied
    written_pages, written, outstream = dump_pages(outstream, written_pages, written)

    return (written, written_pages, written_packets, outstream, granule_delta)


def dump_pages(outstream, written_pages, written):

    print 'Dumping pages',

    while 1:
        pg = outstream.flush()
        if not pg:
            break
        pg.pageno = written_pages
        #print 'writing', pg
        written = written + pg.writeout(fout)
        #print 'written', written, 'bytes so far'
        written_pages = written_pages + 1
        if written_pages % 100 == 0: print written_pages,

    print written_pages
    return written_pages, written, outstream


def get_packetno(seconds, rate):
    needed_samples = seconds * rate
    for z in samples:
        needed_samples = needed_samples - samples[z]
        if needed_samples <= 0:
            break
    return z


def get_samples(filenamein):
    print 'Scanning packets'
    vf = ogg.vorbis.VorbisFile(filenamein)
    pcm_prev = 0
    packetno = 3
    samples = {}
    while 1:
        (buff, bytes, bit) = vf.read(4096)
        if bytes == 0:
            break
        pcm_now = vf.pcm_tell()
        samples[packetno] = pcm_now - pcm_prev
        if samples[packetno] > 1024:
            print "Clipping bogus packet", packetno, "sample size", samples[packetno], "to 1024"
            samples[packetno] = 1024
        pcm_prev = pcm_now
        packetno = packetno + 1
        if packetno % 1000 == 0: print packetno,
    (buff, bytes,bit) = vf.read(4096)
    vinfo = vf.info()
    return samples, vinfo.rate

def renumber_pages(filenamein):
    filenameout = filenamein+".fixed.ogg"
    print
    print "Hole detected! Fixing ogg file and writing it to", filenameout
    fin = open(filenamein, 'rb')
    fout = open(filenameout, 'wb')
    insync = ogg.OggSyncState()
    instream = None
    outstream = None
    pageno = 0

    while 1:
        b = fin.read(65536)
        if not b:
            break
        insync.bytesin(b)
        skipped = 1
        while skipped != 0:
            skipped, page = insync.pageseek()
            if skipped > 0:
                if instream and page.serialno() != serialno:
                    print "we hit a chain boundary, leaving"
                    break
                if not instream:
                    serialno = page.serialno()
                    instream = ogg.OggStreamState(serialno)
                if not outstream:
                    outstream = ogg.OggStreamState(serialno)
                instream.pagein(page)
                #print "in -- ", page
                while 1:
                    try:
                        p = instream.packetout()
                    except ogg.OggError:
                        instream.reset()
                        instream.pagein(page)
                        p = instream.packetout()
                    if not p:
                        break
                    outstream.packetin(p)
                while 1:
                    pg = outstream.flush()
                    if not pg:
                        break
                    pg.writeout(fout)
                    #print "out - ", pg

    fin.close()
    fout.close()
    return filenameout

opts, pargs = getopt.getopt(sys.argv[1:], '', ['analyze', 'join', 'from=', 'upto='])
opt_analyze = opt_join = 0
startpos = -1
endpos = -1

for option, argument in opts:
    if option == '--from':
        try:
            startpos = float(argument)
        except ValueError:
            usage()
    elif option == '--upto':
        try:
            endpos = float(argument)
        except ValueError:
            usage()
    elif option == '--analyze':
        opt_analyze = 1
    elif option == '--join':
        opt_join = 1
    else:
        usage()

if opt_analyze:
    if len(pargs) != 1:
        usage()

    filenamein = pargs[0]
    fin = open(filenamein, 'rb')
    analyze_packets(fin, filenamein)

elif opt_join:
    if len(pargs) != 3:
        usage()

    filenamein = pargs[0]
    try:
        samples, rate = get_samples(filenamein)
    except ogg.vorbis.VorbisError, errorString:
        filenamein = renumber_pages(filenamein)
        samples, rate = get_samples(filenamein)
    fin = open(filenamein, 'rb')

    filenameout = pargs[2]
    fout = open(filenameout, 'wb')

    n, pages, packets, os, grskip = copy_packets(fin, fout, None, 0, 3)
    n, pages, packets, os, grskip = copy_packets(fin, fout, os, 3, 0, pages, packets, grskip)

    filenamein = pargs[1]
    try:
        samples, rate = get_samples(filenamein)
    except ogg.vorbis.VorbisError, errorString:
        filenamein = renumber_pages(filenamein)
        samples, rate = get_samples(filenamein)
    fin = open(filenamein, 'rb')

    n, pages, packets, os, grskip = copy_packets(fin, fout, os, 3, 0, pages, packets, grskip, 1)

else:
    if len(pargs) != 2:
        usage()

    filenamein = pargs[0]
    try:
        samples, rate = get_samples(filenamein)
    except ogg.vorbis.VorbisError, errorString:
        filenamein = renumber_pages(filenamein)
        samples, rate = get_samples(filenamein)
    fin = open(filenamein, 'rb')

    filenameout = pargs[1]
    fout = open(filenameout, 'wb')

    n, pages, packets, os, grskip = copy_packets(fin, fout, None, 0, 3)

    if startpos > -1:
        startpacket = get_packetno(startpos, rate)
    else:
        startpacket = 3

    if startpacket > 5:
        startpacket = startpacket - 2

    if endpos > -1:
        endpacket = get_packetno(endpos, rate)
        count = endpacket - startpacket
    else:
        count = 0

    n, pages, packets, os, grskip = copy_packets(fin, fout, os, startpacket, count, pages, packets, grskip, 1)

它在 get_samples 方法的“vf = ogg.vorbis.VorbisFile(filenamein)”字符串中崩溃。谁能帮我解决这个问题？也许我错误地编译了 vorbis 模块？