Clip & Trim

Starting from v0.8.0, Transcoder offers the option to clip or trim video segments, on one or both ends. This is done by using special DataSource objects that wrap you original source, so that, in case of concatenation of multiple media files, the trimming values can be set individually for each segment.

If Transcoder determines that the video should be decoded and re-encoded (status is TrackStatus.COMPRESSING) the clipping position is respected precisely. However, if your strategy does not include video decoding / re-encoding, the clipping position will be moved to the closest video sync frame. This means that the clipped output duration might be different than expected, depending on the frequency of sync frames in your original file.

TrimDataSource

The TrimDataSource class lets you trim segments by specifying the amount of time to be trimmed at both ends. For example, the code below will trim the file by 1 second at the beginning, and 2 seconds at the end:

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let source: DataSource = UriDataSource(context, uri)
let trim: DataSource = TrimDataSource(source, 1000 * 1000, 2 * 1000 * 1000)
Transcoder.into(filePath)
    .addDataSource(trim)
    .transcode()

It is recommended to always check source.getDurationUs() to compute the correct values.

ClipDataSource

The ClipDataSource class lets you clip segments by specifying a time window. For example, the code below clip the file from second 1 until second 5:

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let source: DataSource = UriDataSource(context, uri)
let clip: DataSource = ClipDataSource(source, 1000 * 1000, 5 * 1000 * 1000)
Transcoder.into(filePath)
    .addDataSource(clip)
    .transcode()

It is recommended to always check source.getDurationUs() to compute the correct values.

Related APIs