There are multiple levels of compression.<p>What typically happens here in the USA is that your local TV station gets, via satellite, a &quot;master feed&quot; which typically is very high bitrate Mpeg4.<p>It then converts it to Mpeg2 (which requires a higher bitrate for the same quality), and compresses it to fit into its 19Mb&#x2F;s ATSC 8VSB broadcast standard.  If your local broadcaster has no subchannels, then you win(1).  The network show gets all 19Mb&#x2F;s of bandwidth.<p>However, if your local station has many subchannels (eg, 24hr weather, local news, re-runs of shows from the 1950s, etc), then they all share that 19 Mb&#x2F;sec and you get far less than 19Mb&#x2F;s allocated to the network show (especially when there is a lot of motion on the subchannel).   The worst I&#x27;ve seen is some ABC affiliates who actually had a <i>SECOND</i> &quot;HD&quot; subchannel for the &quot;livewell&quot; network, which made their network programming look horrible.   I put up a bigger antenna to pull in ABC from a neighboring market &amp; avoid a local affiliate that was doing that.<p>Your local cable company picks up the MPEG2 broadcast and if you&#x27;re lucky, it just passes it through (re-muxing it into a 38Mb&#x2F;s QAM subchannel).   If you&#x27;re unlucky, it takes the already compressed MPEG2 stream and compresses it harder.<p>Back in the &quot;good old days&quot;, the network satellite feeds were not encrypted, and people with the right equipment (Big Ugly Dishes) could pick up the raw network feed, which was reportedly awesome.<p>(1) That is, you win if the equipment doing the MPEG4 -&gt; MPEG2 transcoding doesn&#x27;t suck.   I&#x27;ve consistently seen stations that have a lower bitrate but better quality due to newer encoders doing things like adding repeat field flags to telecined film content, so your mileage may vary.