Most importantly, it contains the encoder delay and replaygain info.
ef363eb mp3enc: write full LAME frame
doc/muxers.texi | 3 +-
libavformat/mp3enc.c | 160 +++++++++++++++++++++++++++++++++++++++-----------
2 files changed, 129 insertions(+), 34 deletions(-)
Upstream: git.libav.org