FFMPEG gop settings.

[Prathamesh]

Hi All,

I'm trying to convert a file using ffmpeg. I want the below parameters in the output file.

Input file : 1920x1080 mp4

output : h264 with .mp4 container.
Profile : Main@3.2 Cabac.
resolution : 720x480
Aspect 16:9
Bitrate: 1500 Kbps CBR
Refrence frames = 2
Gop size = 15 (M=3 , N=15)
Audio : AAC 128 Kbps constant.

I am not able to get the GOP settings right in ffmpeg.

My media info shows the Reference frames=2, but i don't see any Gop Structure.

ffmpeg -i Mi5.mp4 -c:v libx264 -g 15 -bf 2 -refs 1 -flags +cgop -b_strategy 0 -x264opts scenecut=0:b-pyramid=0:b-adapt=0 -profile:v main -level:v 3.2 -s 720x480 -aspect 16:9 -b:v 1500k -bufsize 1835k -nal-hrd cbr output.mp4

Kindly guide me where i'm going wrong.

Regards.

[pandy]

keyintmin and keyintmax at least but not sure if there is any way (normal way, not by modification of log) to force x264 to strict GOP structure (like IBBPBBP... etc).
you may try:

no-scenecut:nal-hrd=cbr:open-gop=0:pic-struct:aud:force-cfr:keyint=15:keyint_min=15

[poisondeathray]

keyinmin and keyinmax at least but not sure if there is any way (normal way, not by modification of log) to force x264 to strict GOP structure (like IBBPBBP... etc).
you may try:

no-scenecut:nal-hrd=cbr:open-gop=0:pic-struct:aud:force-cfr:keyint=15:keyint_min=15

A precise GOP structure can be specified with a qp-file, but it's not available for ffmpeg libx264, only x264cli

But I think OP wants the program mediainfo to indicate something, which isn't necessarily a good idea since it's often wrong