mpegvideo: move the MpegEncContext fields used from arm asm to the beginning

This should reduce the frequency with which the offsets need to be
updated.
ffmpeg: dont print "Conversion failed" if conversion has never started

Found-by: jamrial
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '6a13505c069890cb0e2a07e29fd819a0cf2e73c1'

* commit '6a13505c069890cb0e2a07e29fd819a0cf2e73c1':
  mpegvideo: move the MpegEncContext fields used from arm asm to the beginning

Merged-by: Michael Niedermayer <michaelni@gmx.at>
lavd/fbdev_enc: remove redundant assignments

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/fbdev_enc: move list device code to fbdev_common

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/fbdev_dec: implement fbdev_get_device_list callback

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: add more buffer attributes

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: add pointer checks

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: signal that buffer is still writable after write

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>
lavd/pulse_audio_enc: respect minreq while checking buffer fullness

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>