CODEWITHSUNDEEP
h.264flachevch.265vp9
Techie Android
Techie Android

Reputation: 79

Codec comparison compression/quality

So I'm rebuilding my video library from my file archives (I have my DVDs/Blurays already decoded on my disk) and I want to ensure that I have the best quality files and compression. I know that lossless is not practical for saving space but I do want indistinguishable video/audio quality. I'm using VidCoder and so far have just been comparing the qualities and file sizes between video codecs. I'm thinking about using VP9, I know AV1 will be out soon and I will rebuild it again then using that. For audio I'm thinking of going with FLAC (I really like FLAC and have already used it for my digital CD archive). So which do y'all think is best for what I want? Oh and I don't care about compatibility.

Upvotes: 2

Views: 1503

Answers (5)

Adithyan Ilangovan
Adithyan Ilangovan

Reputation: 151

Introduction

The questions about quantifying quality in the video are always a bit tricky. Nevertheless, there are ways to scientifically quantify the difference to a single metric (at the risk of missing other insights). In the video community, this single metric is typically the BD-RATE. In simple words, it specifies how much bitrate savings can you get when we want the video to be encoded at the same quality.

My Story

We have been recently integrating AV1 encoder into our product for enterprise customers. I am an Encoding Engineer and I was involved in this process. Although I am not allowed to provide all the fine proprietary details, I think can you provide you the high-level results.

Results

After integrating the AV1 encoder, we wanted to benchmark it against our pre-existing encoders. These are the high-level results that we found :

Codec BD-Rate(in %)
H264 -51%
HEVC -29%

If interested, you can read more about that here. Obviously, these results come from the encoder available in our API. And they are averaged over several kinds of inputs and different kinds of output profile renditions (typically ABR). But nevertheless, I expect results in the same ballpark if you use the open-source tool/encoders (ffmpeg from example).

One of my colleagues earlier did a detailed comparison of compression/quality for VP9 vs HEVC. You can check this if interested. In short, VP9 and HEVC could be thought of as almost equivalent.

On another side note, obviously, you have to keep in mind the cost/time taken to do the more "expensive" codecs.

Conclusion

In short, if you don't care so much about compatibility go with AV1 for video encoding and yes FLAC (its lossless audio codec!) is a good choice for audio.

Upvotes: 4

damian101
damian101

Reputation: 111

Vpxenc-vp9 is worse than x264 for encoding to very high quality. And no AV1 encoder can yet beat x265 at very high quality, at least not the official, unmodified ones. These statements are of course not true for all content.

Upvotes: 0

Zimba
Zimba

Reputation: 3681

I've made a test video & encoded to HEVC & AV1.
Advertisements says AV1 can save a HEVC video in 30% of space, for same quality. For some videos I've managed to get over 50%.

A reduction in size is not always the case: one of my videos, a 9MB 7 second HEVC clip encoded by rav1e turned out to be 33MB. Best I got for AV1 is 871KB, from 29MB HEVC file.

SVT-AV1 Encoder Lib v0.8.6 wasn't able to encode this file at all, gave error: Failed to read proper y4m frame delimeter. Read broken. It did give a warning, however, before encoding:

Svt[warn]: The VBR and CVBR rate control modes are a work-in-progress projects, and are only available for demos, experimental and further development uses and should not be used for benchmarking until fully implemented.

For your archive update; if you're looking at saving storage space, you could encode to both HEVC & AV1, then compare file sizes & keep the smaller one. I'm doing the same.

Just a sidenote, work is underway on H.266 & AV2 codecs. AV1 codecs are extremely slow, especially aomenc. SvtAv1Enc & rav1e are both similar speeds I've noticed, but with SvtAv1Enc you have to type extra to specify a good bitrate to maintain "indistinguishable video/audio quality."

image frame from video clip: HEVC vs AV1

Upvotes: -1

Markus Schumann
Markus Schumann

Reputation: 8244

I suggest - don't re-encode. DVD and Blu-ray disc are encoded with a very high quality. If you decode and then encode your video - the quality will be worse.

As far as the audio goes - don't re-encode. Most DVD's have compressed audio (Dolby) so decompressing and then storing it lossless (PCM or FLAC) makes little sense. Your audio files are bigger with no quality gain.

Blu-ray audio can be PCM (rare though) so you may gain a little space advantage but the audio stream is small in comparison to the video stream.

Again for archival purpose - don't reencode.

Upvotes: 0

Peder
Peder

Reputation: 9

Hevc is about 15% better than vp9. Av1 is estimated to be 10-20% better than hevc for 720p and above sources but current builds are around 50x slower to encode compared to hevc.

For audio flac or good aac encoder with high bitrate. Apple or Nero aac encoders perform the best. Use standard aac_lc profile, NOT he-aac, its used for low bitrate scenarios.

Dont use opus for audio its optimized for low to medium bitrate.

Hope this helps, Peder

Upvotes: 0

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