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Message: <blockquote data-quote="mm1352000" data-source="post: 695736" data-attributes="member: 82144">It is not just decompression - it is "decoding". Hence the word [en]codec[ode]; a sort of a collision between encode and decode. Yes there is decompression involved, but there are a lot of other "smarts" used to avoid storing redundant bits. Clever tricks that exploit what we know about how eyes and ears work and what video and audio streams contain that can only really work with video or audio. Don't forget MPEG 2 and h.264 are "lossy" as well (information is lost when you use those formats to store data), as opposed to compression which tends to be lossless.Why do we need codecs? Well, something has to tell the graphics card/DxVA hardware what to decode, and that is the codecs' job. It interacts with the hardware acceleration interface exposed by the video card driver. The video card doesn't "support formats" per se. Rather, it provides hardware that can be directed by a driver to decode certain media formats. I'd imagine some dedicated hardware is also used, but it is not as if the video card knows what to do by itself.Yes, the HDD is a significant bottleneck and the cause of many issues, as is the CPU (potentially) if it is used for decoding. Mismatched codec and video card isn't so much of a factor as mismatched encoder and decoder pairs or to a lesser extent mismatched video and audio codec pairs. h.264 is a huge standard. There is wiggle room within the standard to implement things in different ways, as well as optional parts/features that need only be used if (for example) you are trying to squash the video into the absolutely smallest number of bits possible. We'd like to thing that the broadcasters' encoding equipment all adheres to the standard, however the encoders they use do things in slightly different ways. Some codecs might handle streams produced by certain encoders better than others. In the worst cases a codec might not be able to handle the streams at all. The same applies to hardware acceleration. Hardware acceleration issues are less common, <a href="https://forum.team-mediaportal.com/video-cards-334/warning-pixelation-corruption-h264-channels-82941/" target="_blank">but they do exist</a>.To be honest, there isn't much you can do other than getting advice from other people who watch the same channels as you and have a similar video card to you. There is also <a href="http://bluesky23.yu-nagi.com/en/index.html#DXVAChecker" target="_blank">DxVA checker</a> which allows you to check what h.264 "sub formats" a video card can handle, however at the end of the day it is really trial and error.I wouldn't be looking at the graphics card. I'd look at (in this order):1. HDD.2. Codec.3. Driver.4. Hardware revision.5. Source material.It is easy to get bad HDD performance with the new 4kB "advanced format" drives that are starting to become common. You have to format them correctly or performance really goes down the tubes. That should be something you keep in mind...CPU only really matters if you're not using hardware accelerated h.264 decoding.Don't forget that you all have different cable providers and potentially different hardware revisions and driver versions of the HDPVR. The reason for the first point should be obvious (source format), although perhaps not too relevant given we're talking about analog signals. The same consideration applies to the final two points. Hauppauge might have changed the encoder parameters (=> slight changes in output format => codec compatibility considerations) over time as they fixed issues and learnt how to get the best out of the hardware.</blockquote>

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