If you are downloading subtitles you are already committing piracy, so you might as well download the whole movie in better quality and with less hassle.
> If you are downloading subtitles you are already committing piracy
OpenSubtitles.org[1] claims that downloading amateur transcribed subs and translation-subs is fair use.
> so you might as well download the whole movie in better quality and with less hassle.
My experience is that most movies that are not extremely popular are either not available for torrent download or if they are the audio is not 5.1 surround sound (6 audio channels whose combined bitrate is 448kbps) and the video bitrate is restricted enough to be DVD quality anyways.
Specifically for the video, a 2GB 1080p h264 compressed video will have an average video bitrate less than 2mbps. Its widely acknowledged that h264 is not greater than twice as efficient as MPEG-2 so lets double that to say that a 2GB 1080p h264 compressed video's perceived bitrate quality is no more than 4mbps. Most commercial DVDs will be 480p MPEG-2 compressed video with a bitrate greater than 5mbps.
For perceived video quality (other than diagonal edges and text) bitrate, not resolution, is what matters. Using an neural network AI upscaler such as nnedi3 (or even something less intensive such as the spline algorithm) to pre-upscale 480p video to 720p video will greatly improve the diagonal edges.
Note: If you have 1080p sources that are larger than 2GB and have 5.1 surround sound then you are absolutely correct in saying that the movie will be better quality. I just have not seen those available for download anywhere for the vast majority of movies.
