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Date: Wed, 09 Mar 2011 17:22:41 +0100
From: Andreas Oberritter <obi@linuxtv.org>
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Subject: Re: Simultaneous recordings from one frontend
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On 03/09/2011 03:20 PM, Pascal Jürgens wrote:
> SUMMARY: What's the best available tool for demultiplexing into multiple simultaneous recordings (files)?

The kernel. There's no need to do that in userspace.

Any(*) number of tools may open a demux simultaneously, set up a filter
for the first PID with DMX_OUT_TSDEMUX_TAP and add any(*) number of TS
PIDs with DMX_ADD_PID. Data has to be read from demux, not from the
limited and IMHO obsolete dvr device.

In simplified code for PAT, PMT PID 0x80, Video PID 0x100, Audio PID 0x101:

int fd = open("/dev/dvb/adapter0/demux0", O_RDWR);

struct dmx_pes_filter_params f = {
	.pid = 0, // PAT
	.input = DMX_IN_FRONTEND, // live TV
	.output = DMX_OUT_TSDEMUX_TAP, // TS packets!
	.pes_type = DMX_PES_OTHER, // no decoding
	.flags = DMX_IMMEDIATE_START,
};

uint16_t pid[] = { 0x80, 0x100, 0x101 };

ioctl(fd, DMX_SET_PES_FILTER, &f);
for (int i = 0; i < 3; i++)
	ioctl(fd, DMX_ADD_PID, &pid[i]);

ssize_t r;
unsigned char buf[N * 188];
while ((r = read(fd, buf, sizeof(buf)) >= 0)
	write(1, buf, r);	// write to stdout

close(fd);

If there's no tool using this interface yet, it's probably time to write
or modify one,

Regards,
Andreas

*) Depending on available system resources.