![]() Let's say you want to know how many gigabytes per hour will be spent at a given bit rate. When using x264, you can switch from CRF to CQP for a small performance boost by manually specifying the desired QP value in the "x264 Options" field for example, qp=20 will switch rate control mode to CQP and use a QP value of 20 (min. ![]() When using x264, you can see this quality target (as CRF), but other encoders will hide it. Note that VBR will not use all available bit rate if there's no need to - there is also a quality (QP) target, and if that target can be met at a lower bit rate, it will be lower. The "Max Bitrate" setting, also known as "Peak Bitrate" or "Buffer Size", should typically be set to 2 times your target bit rate to help conceal quality loss in scenarios where the complexity of motion in your video quickly goes up and compression ratios have to be increased, but this might also result in a slight bit rate overshoot in some scenarios. For reference, most modern hard drives can sustain write speeds of around 100 to 140 MBps, or 800 to 1120 Mbps.Ĭhoosing the target bit rate in VBR mode is also straightforward: higher bit rates will yield better quality. This is usually extremely obvious - those parts of the video will show massive artifacts when played in a video player. Please also note that since CQP doesn't care about bit rates, it's possible to end up with bit rates so high that your storage device will fail to write fast enough. If you're not sure what QP value to start with, start with 18. ![]() To get an idea of what kind of bit rates you'll end up with, you'll need to do a test recording of the content (applications, games) that you want to record, then decide if you need to adjust the QP value. Increasing the QP value by +6 will cut file size approximately in half. This is useful if you have limited disk space and want predictable file sizes, but quality may be somewhat unpredictable and there can be moments of visible quality loss.ĬRF (Constant Rate Factor) is unique to the x264 encoder, and works similar to CQP, but it makes some adjustments to account for human perception, improving perceived quality slightly.Ĭhoosing the QP value in CQP mode is straightforward: lower values yield higher quality and larger files, higher values yield lower quality and smaller files. It will change the compression ratio to stay under your bit rate limit. VBR (Variable Bit Rate) uses a bit rate target. If you have a lot of free disk space, this is the preferred method for best video quality, its only downside is that file sizes can be somewhat unpredictable. This means it will always yield a certain level of quality, and the bit rate will vary based on the video's contents. However, it is not necessary for local recording and will usually waste a lot of disk space, so it's preferable to use CQP or VBR instead.ĬQP (Constant Quantization Parameter) uses a flat compression ratio without regard to bit rates. The video encoders available in OBS Studio offer all of the following rate control methods: CBR, VBR and CQP (or CRF in the case with x264).įor livestreaming over the internet, you should always be using CBR as your rate control mode, as it allows for a stable connection with consistent latency. Or, if they don't, you can manually extract them into separate files with MKVToolNix GUI or mkvextract. Most video editors should import all the tracks automatically. In VLC, go to the Audio menu > Audio track, and click on a track. In Media Player Classic-based players, go to the Play menu > Audio Track, and click on a track. In mpv, left-click or right-click on the audio icon in the on-screen controls, or press # (Shift+3 on US English keyboard layouts) Most video players will let you choose only one track to play during playback: Since tracks 5 and 6 were not checked in Settings > Output > Recording, their checkboxes will not affect anything. In this configuration, game audio will go to tracks 1 and 3, microphone will go to tracks 1 and 2, and speakers' audio will go to track 4. On the Audio tab, tracks can be renamed for convenience, and their bit rates can be changed. That's 4 tracks, so 4 checkboxes need to be ticked. Go to Settings > Output > Recording, choose your preferred container format (MKV is highly recommended, as it is crash-safe, and can be remuxed to MP4 for video editors later), then choose how many tracks to record. How to calculate bit rates and file sizes for VBR and CBR (Capturing per-application audio will be added to OBS Studio in the future currently, the win-capture-audio plugin can be installed for this.)ģ. Advanced output mode allows creating a file with multiple audio tracks - for example, you could livestream your game's audio and your microphone, and also record your system sounds, game audio, and microphone into 3 separate tracks for video editing.
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