b6d93282cc
There are corner cases where rate->opos can overflow. For example, if QEMU is started with -audiodev pa,id=audio0, out.frequency=11025 -device ich9-intel-hda -device hda-duplex, audiodev=audio0 and the guest plays audio with a sampling frequency of 44100Hz, rate->opos will overflow after 27.05h and the audio stream will be silent for a long time. To prevent a rate->opos and also a rate->ipos overflow, both are wrapped around after a short time. The wrap around point rate->ipos >= 0x10001 is an arbitrarily selected value and can be any small value, 0 and 1 included. The comment that an ipos overflow will result in an infinite loop has been removed, because in this case the resampling code only generates no more output samples and the audio stream stalls. However, there is no infinite loop. Signed-off-by: Volker Rümelin <vr_qemu@t-online.de> Message-Id: <20220923183640.8314-12-vr_qemu@t-online.de> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
119 lines
3.4 KiB
C
119 lines
3.4 KiB
C
/*
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* QEMU Mixing engine
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*
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* Copyright (c) 2004-2005 Vassili Karpov (malc)
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* Copyright (c) 1998 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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/*
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* Processed signed long samples from ibuf to obuf.
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* Return number of samples processed.
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*/
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void NAME (void *opaque, struct st_sample *ibuf, struct st_sample *obuf,
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size_t *isamp, size_t *osamp)
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{
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struct rate *rate = opaque;
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struct st_sample *istart, *iend;
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struct st_sample *ostart, *oend;
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struct st_sample ilast, icur, out;
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#ifdef FLOAT_MIXENG
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mixeng_real t;
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#else
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int64_t t;
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#endif
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ilast = rate->ilast;
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istart = ibuf;
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iend = ibuf + *isamp;
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ostart = obuf;
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oend = obuf + *osamp;
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if (rate->opos_inc == (1ULL + UINT_MAX)) {
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int i, n = *isamp > *osamp ? *osamp : *isamp;
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for (i = 0; i < n; i++) {
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OP (obuf[i].l, ibuf[i].l);
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OP (obuf[i].r, ibuf[i].r);
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}
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*isamp = n;
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*osamp = n;
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return;
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}
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while (obuf < oend) {
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/* Safety catch to make sure we have input samples. */
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if (ibuf >= iend) {
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break;
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}
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/* read as many input samples so that ipos > opos */
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while (rate->ipos <= (rate->opos >> 32)) {
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ilast = *ibuf++;
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rate->ipos++;
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/* See if we finished the input buffer yet */
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if (ibuf >= iend) {
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goto the_end;
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}
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}
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icur = *ibuf;
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/* wrap ipos and opos around long before they overflow */
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if (rate->ipos >= 0x10001) {
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rate->ipos = 1;
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rate->opos &= 0xffffffff;
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}
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/* interpolate */
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#ifdef FLOAT_MIXENG
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#ifdef RECIPROCAL
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t = (rate->opos & UINT_MAX) * (1.f / UINT_MAX);
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#else
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t = (rate->opos & UINT_MAX) / (mixeng_real) UINT_MAX;
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#endif
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out.l = (ilast.l * (1.0 - t)) + icur.l * t;
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out.r = (ilast.r * (1.0 - t)) + icur.r * t;
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#else
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t = rate->opos & 0xffffffff;
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out.l = (ilast.l * ((int64_t) UINT_MAX - t) + icur.l * t) >> 32;
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out.r = (ilast.r * ((int64_t) UINT_MAX - t) + icur.r * t) >> 32;
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#endif
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/* output sample & increment position */
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OP (obuf->l, out.l);
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OP (obuf->r, out.r);
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obuf += 1;
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rate->opos += rate->opos_inc;
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}
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the_end:
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*isamp = ibuf - istart;
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*osamp = obuf - ostart;
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rate->ilast = ilast;
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}
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#undef NAME
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#undef OP
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