Why does the volume level change between channels?

[Ken W]

Can anyone know why the volume level is different between channels, on Freeview via an Ariel or VM cable TV?

[GavChap]

I've noticed a difference between programmes on the same channel too. Usually HD programmes and films are quieter, but that's due to the way HD is broadcast using Dolby Digital, and the fact films have more headroom for effects. Ads are sometimes louder than programmes, but that's probably due to compression effects to make them seem louder, so you take notice.

BBC HD is also guilty of making their idents (the bits with the cat that turns into a lion, etc) very loud.

[rogerdraig]

anoying as the music being to loud then the talking bits to quiet one day they will invent something that can stick to the volume we want

[Mick]

They already have, it is called a Broadcast limiter, which basically squeezes the sound and keeps it at a contant level and brings up quiet sounds to that level as well without adding distortion. They can also be used to aid talkover, DJ's use such aids to help fade the music whenever they start talking, you may have noticed this, listening to the radio, it's not the DJ loweing the fader on the mixer, but how the sound is processed through the final limiter.

Some channels may use this type of audio processing such as limiting to beef up the sound or to keep volumes at a consistant level, others may not which might explain differences in volume.

Most major Radio stations use such devices to make their broadcasts sound loud and powerful.

[rogerdraig]

i want the device on the tv not at source :P

agreed though yep some channels are fine but it always seems the ones i watch at 2am never do lol leading to lots of volume button pressing

[LSainsbury]

Originally Posted by Mick

...DJ's use such aids to help fade the music whenever they start talking, you may have noticed this, listening to the radio, it's not the DJ loweing the fader on the mixer, but how the sound is processed through the final limiter.

Never knew that...I thought they were using the mixer...