HI
I remember some years back there was discussions about encoding 48000hz files in lame was not working properly because it was not tuned for this frequency.
I don't know if it still the case with lame 3.96.1.

I make tv capture with my tv tuner card and the sound is recorded in pcm through the line-in of my abit be7 motherboard (with integrated realtek alc650 sound). It's an ac97 chip so it is locked to 48000hz, and I don't want to resample if it's not needed.

What is the solution for best quality?
1. encode directly the 48000hz pcm wav with lame 3.96.1
2. resample the 48000hz in 44100hz and then encode with lame 3.96.1?

The files will be encoded in 128kbps cbr and put in an avi with xvid video.

This bitrate is not enough even for 44.1kHz

Since TV capture card is not a source of hiqh-quality audio, and you're going to use 128kbps, I recommend you to resample to 44100Hz to reduce quality degradation.

Thank you for your response
I'll use a more important bitrate (160 or 192) if necessary that's not the problem!

I just want to know if it's safe to use lame with 48000hz material or not.

i believe these days you can make an ogm with vorbis in it. i'm not sure if that handles 48k or not. or you could use the 3ivx stuff and nero's encoder to mux an AAC into an mp4 file...

mp3 has big problems with 48k, because at this samplerate 1/3 of the bandwidth is above sfb21, which means you might as well be encoding at 32Khz. of course, you could set it to encode only short blocks and bypass the problem, but that would sound terrible.

I thought that TV sound was FM, an inherently good sound source. I can remember tapping the FM sound off TV sets and running it through an amp for good quality sound. Are computer TV capture cards not of good quality and unable to capitalize on the quality of FM sound??

here at home we have digital stereo audio from the tv, and somewhere i've heard that this was cd-quality? or am i wrong

Digital audio over the air or cable will have been lossy-compressed.

there's a buttload of audio-formats for TV.

digital TV will NOT have CD quality. hell, it's barely got analog FM quality. if you're lucky you'll get ac3 sound with your DVB, if you're unlucky you'll get mp2. it varies from station to station, and from show to show.

as for analog TV, there's a few format there too. everything from 32khz 10 bit, to regular FM, and several different shades in between.