July 18, 2005, sammo2828 wrote: > 2. Bad reception, or RF noise/interference (e.g. light switch, fridge > turning on/off, etc) corrupts DVB stream. Sometimes this stuffs up audio for > both live tv and recorded shows.
I have spent some effort to isolate this audio-loss problem. I am using DVB-T in Berlin, Germany, Myth from svn some time after the 18.1 release and a Medion 7134 combo card (saa7134-dvb). I have also been getting occasional spontaneous audio losses in PS mode in both LiveTV and recordings, about once every hour, at least on the channels SAT.1 and RTL (both with a single and with two audio streams, by the way). I found out that DVBRecorder::ReadFromDMX() continues to issue occasional (~ every 2 minutes) "Stream Continuity Errors" on ALL pids that have been selected for recording, INCLUDING the audio stream that has broken! This means that DVBRecorder::ReadFromDMX() still gets data from the card for the affected stream. However, having added some additional debug messages, I found out that DVBRecorder::LocalProcessDataPS() is no longer calling ringBuffer->Write() for the lost audio stream (which is quite a good reason for it being lost, actually...). On the other hand, some (very limited, though) testing indicates that I do not get these audio losses with TS recording. Conclusion: There seems to be some issue within the transcode.c infrastructure (instant_repack(), send_ipack()) for rebuilding the stream, which is bypassed in TS mode. It is beyond my qualification to find out what exactly transcode.c is doing wrong... > Changing from PS to TS also has no effect because I find that myth ALWAYS > records all audio tracks. Hmmm, while the latter is definitely true, it might not actually be a reason for the changing to have no effect. For the data processing (from DVBRecorder::ReadFromDMX() on) is completely different for TS vs. PS modes. Have you ACTUALLY experienced spontaneous audio losses (your "class 2") in TS mode as well?? Hope this helps, Marek
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