Here is why the "old" codec holds the real throne. Season 01 of Game of Thrones was shot on the Arri Alexa, but it was treated like film. Cinematographer Alik Sakharov used natural firelight and candlelight. The result was a show that looked oily and warm —specifically in the Winterfell and Vaes Dothrak sequences.
Look for the or DIMENSION releases of Season 01. Look for the H264 container. MKV, not MP4. Bitrate hovering around 8,000 kbps.
The first season relied on practical effects and natural lighting. It wasn't the dragons-and-explosions spectacle of Season 06. It was dialogue in dark rooms. H264, with its higher bitrate per file size (when done properly), preserves the macroblocking in the shadows of the crypts of Winterfell. In the H265 version, those shadows become a smooth, plastic void. In the H264 version, you can see the texture of the stone walls. If you own the 4K Blu-rays, keep them. They are reference quality. But if you want to feel the way audiences felt in 2011—when the show was a dangerous, dirty, low-fantasy political thriller—seek out the old scene releases.
The original releases preserve the "sallow" look of Season 01. Winterfell was desaturated, leaning toward grey-green. The Dothraki sea was a harsh, bleached yellow, not a lush gold. By locking the image in H264 (a codec that struggles with sharp edges but handles gradients beautifully), the encoding actually softens the digital harshness of the Alexa sensor. It makes the wigs look slightly less obvious. It makes the CGI for the direwolves blend into the background. Why "H264" specifically? You might ask: Isn't H265 better? Technically, yes. It compresses more information into less space. But for Season 01, H264 is the perfect bottleneck.
It is not sharper. It is not cleaner. It is truer . And in the game of codecs, you either preserve the grain, or you die.
