Adaptive multi-pass video encoder control

A method, comprising:

• in a first pass of a multi-pass encoding scheme, encoding a video stream using a first constant rate factor (CRF) to generate a compressed video stream;
• determining a rate distortion cost associated with the compressed video stream;
• determining whether the rate distortion cost is above a cost threshold;
• upon determining the rate distortion cost is above the cost threshold,
• calculating a second CRF as:
• CRF
• 2
• =
• CRF
• 1
• +
• 1
• α
• ⁢
• log
• ⁡
• (
• B
• ma
• ⁢
• ⁢
• x
• B
• 1
• )
• where CRF1 is the first CRF,
• CRF is the second CRF,
• α is a constant,
• Bmax is the target maximum bitrate, and
• B1 is the bitrate of the compressed video, and
• in an intermediate pass of the multi-pass encoding scheme, encoding the video stream associated with the compressed video stream using the second CRF;
• or
• upon determining the rate distortion cost is below the cost threshold,
• in a final pass of the multi-pass encoding scheme, encoding the video stream associated with the compressed video stream using the first CRF and a target bitrate.

A non-transitory computer-readable storage medium having stored thereon computer executable program code which, when executed on a computer system, causes the computer system to perform steps comprising:

• determining whether a quality of a compressed video is above a cost threshold, the compressed video being encoded using a first constant rate factor (CRF);
• upon determining the quality of the compressed video is above a cost threshold,
• calculating a second CRF based on the first CRF as:
• CRF3={circumflex over (α)} log(Bmax)+{circumflex over (β)}
• where
• α
• ^
• =
• log
• ⁡
• (
• B
• 1
• )
• -
• log
• ⁡
• (
• B
• 2
• )
• CRF
• 1
• -
• CRF
• 2
• ,
• and
• {circumflex over (β)}=log(B1)−{circumflex over (α)}CRF1
• CRF1 is a CRF used to encode the video before using the first CRF,
• CRF2 is the first CRF,
• α is a constant,
• Bmax is the target maximum bitrate,
• B1 is a bitrate associated with CRF1
• B2 is the bitrate of the compressed video, and
• encoding a video associated with the compressed video using the second CRF;
• or
• upon determining the quality of the compressed video is below a cost threshold,
• encoding a video associated with the compressed video using the first CRF and a target bitrate.

A method, comprising:

• in a first pass of a multi-pass encoding scheme, encoding a video stream using a first constant rate factor (CRF) to generate a first compressed video stream;
• determining a rate distortion cost associated with the first compressed video stream;
• determining whether the rate distortion cost is above a cost threshold;
• upon determining the rate distortion cost is above the cost threshold,
• calculating a second CRF as:
• CRF3={circumflex over (α)} log(Bmax)+{circumflex over (β)}
• where,
• α
• ^
• =
• log
• ⁡
• (
• B
• 1
• )
• -
• log
• ⁡
• (
• B
• 2
• )
• CRF
• 1
• -
• CRF
• 2
• ,
• and
• {circumflex over (β)}=log(B1)−{circumflex over (α)}CRF1
• CRF1 is a CRF used to encode the video before using the first CRF,
• CRF2 is the first CRF,
• α is a constant,
• Bmax is the target maximum bitrate,
• B1 is a bitrate associated with CRF1
• B2 is the bitrate of the compressed video, and
• in an intermediate pass of the multi-pass encoding scheme, encoding the video stream using the second CRF;
• or
• upon determining the rate distortion cost is below the cost threshold,
• in a final pass of the multi-pass encoding scheme, encoding the video using the first CRF and a target bitrate.