320kBps BBC HD stream

[GRC]

I'd like to see if this would be acceptable for uploading at TTD.

This page describes the stream as "320kbps AAC-LC", and this Wiki gives more tech detail.

Although the Wiki describes the compression basis as lossy, it has some preferable aspects to FM - it displays no background hiss, is totally free from interference, and has no 19kHz pilot tone submerged in the audio.

Someone in the blog compares the two as follows;

"The 320kbps aac-lc stream is ... higher definition than current DAB/Freeview/satellite in the UK (192kbps mp2 at best for BBC radio) or FM (which is Optimod-processed, top cut to 15kHz, and NICAM (14 bit quantisation at best) carried to the transmitters)."

It seems from other sources that the digital links between broadcaster and FM transmitters function at a 32kHz sample rate, so begs the question - which is the more 'lossy' -

FM going through Optimod processing, top cut to 15kHz, and NICAM (14 bit, 32kHz sampling in the links to the transmitters, or

The 320kB stream using (apparently) 44.1kHz all the way until the compression into the stream at point of delivery?




Discuss?

[Unidecker]

deff not...

[wastegate]

all-digital 320 kbps aac....that is probably the highest quality audio broadcast format we'll ever see. doubt we'll ever see lossless broadcasts/streams, at least from mainstream sources as it uses too much bandwidth.

most analog FM broadcasts are lossy sourced these days anyway as CDs have been mostly phased out. the songs get played from a hard disk drive, and I doubt they are playing wav, flac, or alac.

but even a lossless sourced analog FM with its dynamics compression, hum, and interference would lose to an all-digital 320 kbps lossy broadcast

surprised this hasn't gotten more discussion...guess teh gurus of quality don't much care...upload em to DIME

[dorrcoq]

Originally Posted by wastegate

all-digital 320 kbps aac....that is probably the highest quality audio broadcast format we'll ever see. doubt we'll ever see lossless broadcasts/streams, at least from mainstream sources as it uses too much bandwidth.

most analog FM broadcasts are lossy sourced these days anyway as CDs have been mostly phased out. the songs get played from a hard disk drive, and I doubt they are playing wav, flac, or alac.

but even a lossless sourced analog FM with its dynamics compression, hum, and interference would lose to an all-digital 320 kbps lossy broadcast

surprised this hasn't gotten more discussion...guess teh gurus of quality don't much care...upload em to DIME

Nice ratio, weenie!

[paddington]

320kbps AAC is lossy. TTD FAQ / policy doesn't allow for that.

thanks for checking

[jabulon]

For the record, a real HD audio stream should at least have a sampling rate of 96 kHz or higher.

[GRC]

It's all a question of perspective; when the bitrate used on the other BBC streams is 196kBs, the 320kBs one is the one with the 'higher definition' and has been tagged HD to differentiate it from the others.

They're not using HD in a commercial sense, merely as an identifier within their own set of streams.

[GRC]

Originally Posted by jameskg

320kbps AAC is lossy. TTD FAQ / policy doesn't allow for that.

thanks for checking

OK.