Configure FFmpeg MPEG PS Muxrate and Buffer Size

Configuring the multiplexing rate and video buffer size in FFmpeg’s MPEG Program Stream (MPEG-PS) muxer is crucial for producing streams that comply with strict hardware decoding standards, such as DVD-Video or legacy broadcast hardware. This article explains how to use the -muxrate option to control the total stream output rate and how to configure the video encoder’s -bufsize and -maxrate parameters to manage the Video Buffer Verifier (VBV) system.

Setting the Multiplexing Rate (-muxrate)

The multiplexing rate defines the constant bit rate of the combined audio, video, and metadata packets in the output Program Stream. By default, FFmpeg calculates a variable mux rate based on the input streams, but legacy systems often require a strict constant rate.

To set a constant multiplexing rate, use the -muxrate option. The value is specified in bits per second (bps), but you can use metric suffixes like k (kilobits) or M (megabits).

ffmpeg -i input.mp4 -f mpeg -muxrate 10080000 output.mpg

In this example, -f mpeg specifies the MPEG Program Stream format, and -muxrate 10080000 forces a constant multiplex rate of 10.08 Mbps (the standard maximum rate for DVD-Video).

Setting the Video Buffer Size (-bufsize and -maxrate)

To prevent the decoder’s buffer from overflowing or underflowing, you must configure the Video Buffer Verifier (VBV) parameters at the video encoder level. This requires setting both the maximum video bitrate (-maxrate) and the buffer size (-bufsize).

• -maxrate: Sets the absolute peak bitrate allowed for the video stream.
• -bufsize: Sets the size of the decoder’s input buffer. This controls how often the bitrate is recalculated to prevent buffer violations.

For standard DVD-compliant MPEG-2 Program Streams, the maximum video bitrate is typically capped at 9.8 Mbps, and the VBV buffer size is strictly limited to 224 KB (which translates to 1,835,008 bits, or 1835k).

ffmpeg -i input.mp4 -c:v mpeg2video -b:v 5000k -maxrate 9000k -bufsize 1835k output.mpg

Complete Configuration Example

When configuring both parameters, the multiplexing rate (-muxrate) must always be higher than the combined maximum bitrates of your video and audio streams to account for container overhead.

The following command demonstrates a complete configuration for an MPEG-2 Program Stream with a fixed mux rate and an explicit VBV buffer configuration:

ffmpeg -i input.mp4 \
  -c:v mpeg2video -b:v 6000k -maxrate 8000k -bufsize 1835k \
  -c:a mp2 -b:a 224k \
  -f vob -muxrate 10080000 \
  output.mpg

Parameter Breakdown: * -c:v mpeg2video: Encodes the video stream to MPEG-2. * -b:v 6000k: Targets an average video bitrate of 6 Mbps. * -maxrate 8000k: Prevents the video bitrate from exceeding 8 Mbps. * -bufsize 1835k: Sets the VBV buffer size to 224 KB (DVD standard). * -c:a mp2 -b:a 224k: Encodes the audio to MP2 at 224 kbps. * -f vob: Selects the DVD-Video variant of the MPEG Program Stream muxer. * -muxrate 10080000: Locks the final multiplexed file to a constant 10.08 Mbps stream.