In a hurry?
Don't have time to read a long article about video quality and resolutions? A good start is to enable the following flavours:
- Basic/Small - WEB/MBL (H264/600)
- SD/Large - WEB/MBL (H264/1500)
- UHD/4K- WEB (H264/8000)
In the Kaltura KMC it is possible to change the transcoding settings, these settings determine what formats (flavours) uploaded videos are converted to.
The following video formats are available to choose from:
|0||Source||N/A||N/A||AUTO x AUTO|
|1||Mobile (3GP)||3gp||mpeg4||364||320 x AUTO|
|2||Basic/Small - WEB/MBL (H264/400)||mp4||h264||464||480 x AUTO|
|3||Basic/Small - WEB/MBL (H264/600)||mp4||h264||664||640 x AUTO|
|4||SD/Small - WEB/MBL (H264/900)
||mp4||h264||964||640 x AUTO|
|5||SD/Large - WEB/MBL (H264/1500)||mp4||h264||1628||1024 x 720|
|6||HD/720 - WEB (H264/2500)||mp4||h264||2628||AUTO x 720|
|7||HD/1080 - WEB (H264/4000)||mp4||h264||4128||AUTO x 1080|
|8||WebM||webm||vp8||846||AUTO x 360|
|39||UHD/4K- WEB (H264/8000)||mp4||h264||8256||AUTO x 2160|
None of the flavours in Kaltura will change the aspect-ratio of the video. All the dimensions where AUTO is part of the dimension, the AUTO part will be replaced with a fitting value so that the aspect-ratio can be kept intact. The notable exception being SD/Large - WEB/MBL (H264/1500), this flavour will not change the aspect either, but height and width of the video will always be kept under 1024 and 720 respectively.
Bitrate and quality
The bitrate is a measure of how many bits pr second that the video-stream are allowed to use, so it has a direct impact on how many megabytes (1 byte = 8 bits) pr second the client has to download.
|Bitrate (bps)||Required download speed|
These speeds are the absolute minimum required for the client internet connection to smoothly play a video, and even though the speeds might seem small it is worth noting that the speed needs to be sustained continuously throughout the video playback, even on bad (wifi) connections and in rural areas.
The available flavours can be categorised into 5 different types, which each have some special characteristics.
Relevant for flavour id 0:
The source type designate that this flavour is the original file uploaded to Kaltura, so the format, codec, bitrate and resolution depends on the uploaded file. If you disable this flavour, Kaltura will delete the original video once all other flavours are converted, this can save you some space on the server. If you plan to use the video editor in Kaltura it is required to have the source flavour.
Relevant for flavour id 1:
This format accompanied the introduction of 3G phones, and is used to support the then modern video-phones. Most modern phones can't play this format, so unless you have a big userbase living in a timeboble from the early two-thousands you properly don't want to use it.
Relevant for flavour id 8:
Initially released in 2010, the WebM format was supposed to be the new open standard for video online, but as it is still not supported in Internet Explorer or Safari without additional plugins, it doesn't serve much purpose today. We do not recommend that you enable WebM.
Relevant for flavour ids 2, 3, 4, 5, 6 and 7:
These formats have a static bitrate and resolution, meaning that even though they are enabled the flavour won't be created if the source video have a lower resolution or lower bitrate.
Relevant for flavour id 39:
This format is a catch-all format for the best possible video quality (up to 4K), this flavour will always be created even if the source video is of lower quality.
What flavours to enable
Choosing the flavours to enable might seem complex, and there is quite a few things to consider, but our recommendation is to enable Source, Basic/Small - WEB/MBL (H264/600), SD/Large - WEB/MBL (H264/1500) and HD/1080 - WEB (H264/4000). If you want to be able to stream higher resolution than 1080, you can enable UHD/4K- WEB (H264/8000) instead of HD/1080 - WEB (H264/4000) (see the section on flavour types above)
The Source is to make sure that the original video is kept and that the edit functions in Kaltura works. The other 3 flavours represents a good spread of quality for all connections while not generating too much data to store.
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