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muxer_pass: Change PAT and PMT rewriting code so that it does not modify the TS packets in-place. These are shared buffers (with other subscriptions to the same service) and was causing CC errors in the PAT packets when there were multiple simultaneous subscriptions to the same service using TS passthrough. Initial patch by adamsutton - see recent IRC logs.

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This commit is contained in:
Dave Chapman 2014-06-25 21:36:51 +01:00
parent 6b08fc4108
commit f1611329ef
1 changed files with 47 additions and 35 deletions
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82
src/muxer/muxer_pass.c
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@ -217,37 +217,28 @@ pass_muxer_build_pmt(const streaming_start_t *ss, uint8_t *buf0, int maxlen,
/*
* Rewrite a PAT packet to only include the service included in the transport stream.
*
* This is complicated by the need to deal with PATs that span more than one transport
* stream packet. In that scenario, we replace the 2nd and subsequent PAT packets with
* NULL packets (PID 0x1fff).
*
* Return 0 if packet can be dropped (i.e. isn't the starting packet
* in section or doesn't contain the currently active PAT)
*/
static int
pass_muxer_rewrite_pat(pass_muxer_t* pm, unsigned char* tsb)
{
int pusi = tsb[1] & 0x40;
int cur = tsb[10] & 0x01;
/* NULL packet */
if (!pusi) {
tsb[1] = 0x1f;
memset(tsb+2, 0xff, 186);
/* Ignore next packet or not start */
if (!pusi || !cur)
return 0;
}
/* Ignore Next (TODO: should we wipe it?) */
if (!(tsb[10] & 0x1)) {
return 0;
}
/* Some sanity checks */
if (tsb[4]) {
tvherror("pass", "Unsupported PAT format - pointer_to_data %d", tsb[4]);
return 1;
return -1;
}
if (tsb[12]) {
tvherror("pass", "Multi-section PAT not supported");
return 2;
return -2;
}
/* Rewrite continuity counter, in case this is a multi-packet PAT (we discard all but the first packet) */
@ -266,7 +257,7 @@ pass_muxer_rewrite_pat(pass_muxer_t* pm, unsigned char* tsb)
memset(tsb + 21, 0xff, 167); /* Wipe rest of packet */
return 0;
return 1;
}
/**
@ -429,39 +420,60 @@ static void
pass_muxer_write_ts(muxer_t *m, pktbuf_t *pb)
{
pass_muxer_t *pm = (pass_muxer_t*)m;
unsigned char* tsb;
int e;
uint8_t tmp[188], *tsb, *pkt = pb->pb_data;
size_t len = pb->pb_size;
/* Rewrite PAT/PMT in operation */
if (pm->m_config.m_flags & (MC_REWRITE_PAT | MC_REWRITE_PMT)) {
tsb = pb->pb_data;
len = 0;
while (tsb < pb->pb_data + pb->pb_size) {
int pid = (tsb[1] & 0x1f) << 8 | tsb[2];
/* PAT */
if (pm->m_config.m_flags & MC_REWRITE_PAT && pid == 0) {
if (pass_muxer_rewrite_pat(pm, tsb)) {
tvherror("pass", "PAT rewrite failed, disabling");
pm->m_config.m_flags &= ~MC_REWRITE_PAT;
}
/* PMT */
} else if (pm->m_config.m_flags & MC_REWRITE_PMT && pid == pm->pm_pmt_pid) {
if (tsb[1] & 0x40) { /* pusi - the first PMT packet */
memcpy(tsb, pm->pm_pmt, 188);
tsb[3] = (pm->pm_pmt[3] & 0xf0) | pm->pm_pmt_cc;
/* Process */
if ( ((pm->m_config.m_flags & MC_REWRITE_PAT) && (pid == 0)) ||
((pm->m_config.m_flags & MC_REWRITE_PMT) &&
(pid == pm->pm_pmt_pid)) ) {
/* Flush */
if (len)
pass_muxer_write(m, pkt, len);
/* Store new start point (after this packet) */
pkt = tsb + 188;
len = 0;
/* PAT */
if (pid == 0) {
memcpy(tmp, tsb, sizeof(tmp));
e = pass_muxer_rewrite_pat(pm, tmp);
if (e < 0) {
tvherror("pass", "PAT rewrite failed, disabling");
pm->m_config.m_flags &= ~MC_REWRITE_PAT;
}
if (e)
pass_muxer_write(m, tmp, 188);
/* PMT */
} else if (tsb[1] & 0x40) { /* pusi - the first PMT packet */
pm->pm_pmt[3] = (pm->pm_pmt[3] & 0xf0) | pm->pm_pmt_cc;
pm->pm_pmt_cc = (pm->pm_pmt_cc + 1) & 0xf;
} else {
/* Nullify packet */
tsb[1] = 0x1f;
memset(tsb+2, 0xff, 186);
pass_muxer_write(m, pm->pm_pmt, 188);
}
/* Record */
} else {
len += 188;
}
/* Next packet */
tsb += 188;
}
}
pass_muxer_write(m, pb->pb_data, pb->pb_size);
if (len)
pass_muxer_write(m, pkt, len);
}