Decoding: duration of the stream, in stream time base.
If a source file does not specify a duration, but does specify
a bitrate, this value will be estimated from bitrate and file size.
Encoding: May be set by the caller before avformat_write_header() to
provide a hint to the muxer about the estimated duration.
Decoding: duration of the stream, in stream time base. If a source file does not specify a duration, but does specify a bitrate, this value will be estimated from bitrate and file size.
Encoding: May be set by the caller before avformat_write_header() to provide a hint to the muxer about the estimated duration.