Add extradata to the beginning of the filtered packets.

The additional argument specifies which packets should be filtered. It accepts the values:

a

add extradata to all key packets, but only if local_header is set in the flags2 codec context field

k

add extradata to all key packets

e

add extradata to all packets

If not specified it is assumed k.

For example the following ffmpeg command forces a global header (thus disabling individual packet headers) in the H.264 packets generated by the libx264 encoder, but corrects them by adding the header stored in extradata to the key packets:

ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts