Diff Rate Controls Modes for MPEG-4 AVC H.264 with/without Intel Quick Sync

[mike23]

When I try to re-encode a video into a MP4 container (with XMedia Recode) I have the choice between

MPEG-4 AVC H.264
and
MPEG-4 AVC H.264 (Intel quick sync)

Surprisingly both codecs have some different Bitrate Control Modes:

MPEG-4 AVC H.264:
- ABR (Average Bitrate)
- 2-pass ABR (2-pass average bitrate)
......

MPEG-4 AVC H.264 (Intel Quick Sync):
- ABR (average bitrate)
- VBR (variable bitrate)
- ICQ (Intelligent constant quality)
.....


Why is there no 2-pass encoding for the second encoding but only for the first?

Whats the difference between ABR and VBR?

Which Bitrate Control Mode is the best for MPEG-4 AVC H.264 (Intel Quick Sync)?

[benwaggoner]

I imagine the first option uses the x264 software encoder, which provides higher quality and a lot more flexibility.

For QuickSync, ICQ is supposed to provide the best quality @ bitrate, but I've not messed with it in ages. Modern computers can encode x264 so quickly that messing with HW H.264 is rarely useful outside of live game streaming.