In the absence of a loop-back cable, you can use software to record from the saa7134-alsa module to a sound card. This allows a digital path with programs like tvtime. However, the process of moving the data from the saa7134 chip to your sound card will add a delay. Unfortunately, software can not predict the future and you need to delay the video in order to sync the audio and video. The mplayer program has options to adjust this.
arecord -r 32000 -c 2 -f S16_LE --device='hw:1,0' | aplay -r 32000 -c 2 -f S16_LE --device='hw:0,0'
The aplay parameter must match the arecord parameters (execept the device). The parameters will be determined by the saa7134 signal source (analog NTSC, broadcast, cable, etc?). The above command is typical for a system with a single sound card and tv capture card. The commands,
- arecord -L
- arecord -l
- aplay -L
- aplay -l
can be helpful on obtaining information on the devices to use.
It can be done; However, loopback cables are very in-expensive so if your hardware supports it, loop the saa7134 audio out to a sound card input.