Hi,

I have been using an encoding method to convert video files (such as .mkv and .avi) to iPod .m4v format. Usually everything turns out ok.

However, I have found that in some cases, things don't go entirely to plan, in many .avi files i have tried to encode, I have found that I keep getting the following errors:

[mp3 @ 0x1928a30]mdb:496, lastbuf:0 skipping granule 0
Last message repeated 1 times
[mp3 @ 0x1928a30]mdb:496, lastbuf:0 skipping granule 1
Last message repeated 1 times
[mp3 @ 0x1928a30]mdb:511, lastbuf:329 skipping granule 0
Last message repeated 1 times
[mp3 @ 0x1928a30]mdb:511, lastbuf:329 skipping granule 1
[mpeg4 @ 0x1928070]Invalid and inefficient vfw-avi packed B frames detected
frame= 663 fps= 88 q=10.0 size= 1132kB time=27.57 bitrate= 336.4kbits/s




I do not understand what the "lastbuf:0 skipping granule" lines mean, and also the "invalid and innefficient vfw-avi B frames detected" line means.



Could someone explain this to me? and explain how to resolve this error?



It seems that every time this shows up (particularly the "invalid and innefficient etc... line), the video appears to jerk slightly around every second. And in other cases, I have found that the audio completely falls out of sync with the video (as far as minutes behind the video)



If its any help I'll give the ffmpeg lines I am using:


Code:
ffmpeg -y -i "%encode_file%" -acodec libfaac -ab 112kb -ac 2 -vol %vol% -ar 44100 -vcodec libx264 -level 21 -aspect %aspect% -b 384kb -r %fps% -coder 0 -croptop %croptop% -cropbottom %cropbottom% -cropleft %cropleft% -cropright %cropright% -s %dimensions% -metadata title="%title%" -f psp -cmp +chroma -flags +loop -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 -deblockalpha 0 -deblockbeta 0 -refs 1 -sc_threshold 40 -flags2 +mixed_refs -qdiff 4 -qcomp 0.60 -complexityblur 20.0 -qblur 0.5 -g 250 -keyint_min 25 -subq 2 -me_range 16 -me_method dia -qmin 10 -qmax 51 -i_qfactor 0.71 -pass 1 -threads %threads% -t %encode_time% -ss %encode_start_position% "%output_file%.m4v"
ffmpeg -y -i "%encode_file%" -acodec libfaac -ab 112kb -ac 2 -vol %vol% -ar 44100 -vcodec libx264 -level 21 -aspect %aspect% -b 384kb -r %fps% -coder 0 -croptop %croptop% -cropbottom %cropbottom% -cropleft %cropleft% -cropright %cropright% -s %dimensions% -metadata title="%title%" -f psp -cmp +chroma -flags +loop -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 -deblockalpha 0 -deblockbeta 0 -refs 3 -sc_threshold 40 -flags2 +mixed_refs -qdiff 4 -qcomp 0.60 -complexityblur 20.0 -qblur 0.5 -g 250 -keyint_min 25 -subq 8 -me_range 16 -me_method umh -qmin 10 -qmax 51 -i_qfactor 0.71 -pass 2 -threads %threads% -t %encode_time% -ss %encode_start_position% "%output_file%.m4v") else (
ffmpeg -y -i "%encode_file%" -acodec libfaac -ab 112kb -ac 2 -vol %vol% -ar 44100 -vcodec libx264 -level 21 -aspect %aspect% -b 384kb -r %fps% -coder 0 -croptop %croptop% -cropbottom %cropbottom% -cropleft %cropleft% -cropright %cropright% -s %dimensions% -metadata title="%title%" -f psp -cmp +chroma -flags +loop -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 -deblockalpha 0 -deblockbeta 0 -refs 1 -sc_threshold 40 -flags2 +mixed_refs -qdiff 4 -qcomp 0.60 -complexityblur 20.0 -qblur 0.5 -g 250 -keyint_min 25 -subq 2 -me_range 16 -me_method dia -qmin 10 -qmax 51 -i_qfactor 0.71 -pass 1 -threads %threads% -ss %encode_start_position% "%output_file%.m4v"
ffmpeg -y -i "%encode_file%" -acodec libfaac -ab 112kb -ac 2 -vol %vol% -ar 44100 -vcodec libx264 -level 21 -aspect %aspect% -b 384kb -r %fps% -coder 0 -croptop %croptop% -cropbottom %cropbottom% -cropleft %cropleft% -cropright %cropright% -s %dimensions% -metadata title="%title%" -f psp -cmp +chroma -flags +loop -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 -deblockalpha 0 -deblockbeta 0 -refs 3 -sc_threshold 40 -flags2 +mixed_refs -qdiff 4 -qcomp 0.60 -complexityblur 20.0 -qblur 0.5 -g 250 -keyint_min 25 -subq 8 -me_range 16 -me_method umh -qmin 10 -qmax 51 -i_qfactor 0.71 -pass 2 -threads %threads% -ss %encode_start_position% "%output_file%.m4v")

I am fairly new to ffmpeg so I wasnt able to address this issue myself, and the batch script I am using with these options was not created by me personally.


Any help would be greatly appreciated as I am keen to resolve this error.


Thanks