For badly interleaved files, interleave packets from multiple tracks
at the demuxer level can trigger seeking back and forth, which can be
dramatically slow depending on the protocol. Demuxer level interleave
can be useless sometimes, e.g., reading mp4 via http and then
transcoding/remux to DASH. Disable this option when you don't need the
demuxer level interleave, and want to avoid the IO penalizes.
Co-authored-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>