Codecs supported

Video:

• H264
• VP8
• H265 (since build 5.2.1803)

Audio:

• Opus
• AAC
• G711 (PCMA, PCMU)
• G722

The cases when transcoding is enabled

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enables the picture width rounding up: in this case the resolution will be 854x480.

Transcoder output stream audio and video synchronization

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Vertical video aspect ratio calculation

Since build 5.2.1911, WCS detects a stream published orientation by picture width and height and keeps aspect ratio as follows:

1. For horizontal (landscape) video (a picture width is greater than or equal to height) the height value of transcoding profile will be applied to picture height, a picture width to transcode will be calculated by picture height. For example, a source stream with 1920x1080 (16:9) resolution will be transcoded to 640x360 resolution by profile with height: 360 .

2. For vertical (portrait) video (a picture width is less than height) the height value of transcoding profile will be applied to picture width, a picture heignht to transcode will be calculated by picture width. For example, a source stream with 1080x1920 (9:16) resolution will be transcoded to 360x640 resolution by profile with height: 360 .

Transcoder output stream audio and video synchronization

By default transcoder does not synchronize output stream audio and video, leaving sinchronization value as is. This can lead to out of audio and video sync in stream transcoded. To prevent this, the pacer buffer is added in build 5.2.543 which can be enabled with the following parameter

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encoder_priority=FF

2. Default watermark (black picture) will be used if watermark file is damaged or absent

Symptoms: black picture in output stream when watermark is added, there is a message in server log 

Wrong watermark file format. Should be PNG.

Solution: use only correct PNG file to add watermark