HOWTO: Convert MPEG2 into MP4

cato4liberty · 02-06-2006, 12:06 PM

I use the following steps to convert video capture MPEG2 files into MP4 format (H.264 and AAC). Basically, the video will be converted into H.264 using two-pass x264, and the PCM audio will be converted into AAC. The H.264 video and AAC audio will then be muxed into the MP4 container.

In a few test runs I noticed that MP4 took up less than half the space of MPEG2 at a similar quality level.

MPEG2: 18 MB (640x480 @ 29.9 fps, 2662 kbps video, 128 kbps 48 khz audio)
MP4: 8.2 MB (640x480 @ 29.9 fps, 1002 kbps video, 125k 48 khz audio)

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Steps to convert MPEG2 into MP4

Demux MPEG2 into M2V and MP2

Code:

mpeg_ps_extract --video --audio myfile.mpeg

Convert video: M2V to x264 - Pass 1

Code:

mencoder -ovc x264 -x264encopts pass=1:\
qcomp=0.75:subq=5:4x4mv:8x8dct:frameref=2:bframes=3:b_pyramid:\
weight_b:log=-1 -ofps 29.97 -vf scale=640:480 -passlogfile \
x264logfile myfile.m2v -of rawvideo -o myfile.264

Convert video: M2V to x264 - Pass 2

Code:

mencoder -ovc x264 -x264encopts pass=2:bitrate=1000:qcomp=0.75:\
subq=5:4x4mv:8x8dct:frameref=2:bframes=3:b_pyramid:weight_b:\
log=-1 -ofps 29.97 -vf scale=640:480 -passlogfile x264logfile \
myfile.m2v -of rawvideo -o myfile.264

Extract audio into PCM WAV

Code:

ffmpeg -v 0 -i myfile.mpeg -vn myfile.wav

Convert audio: PCM WAV to AAC

Code:

faac --mpeg-vers 4 -b 128 -c 44100 myfile.wav -o myfile.aac

Mux into MP4: H.264 video and and AAC audio

Code:

MP4Box -add myfile.264:fps=29.97 -add myfile.aac myfile.mp4

cato4liberty · 02-06-2006, 12:08 PM

Here are details of the input file (MPEG2) and the output file (MP4).

Details of the input file (MPEG2)

Code:

$ midentify myfile.mpeg
ID_VIDEO_ID=0
ID_AUDIO_ID=0
ID_FILENAME=myfile.mpeg
ID_DEMUXER=mpegps
ID_VIDEO_FORMAT=0x10000002
ID_VIDEO_BITRATE=2662400
ID_VIDEO_WIDTH=480
ID_VIDEO_HEIGHT=480
ID_VIDEO_FPS=29.970
ID_VIDEO_ASPECT=1.3333
ID_AUDIO_CODEC=mp3
ID_AUDIO_FORMAT=80
ID_AUDIO_BITRATE=128000
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
ID_LENGTH=60.17
ID_VIDEO_CODEC=mpegpes

Details of the output file (MP4)

Code:

$ midentify myfile.mp4
ID_VIDEO_ID=0
ID_AUDIO_ID=1
ID_FILENAME=myfile.mp4
ID_DEMUXER=mov
ID_VIDEO_FORMAT=avc1
ID_VIDEO_BITRATE=0
ID_VIDEO_WIDTH=640
ID_VIDEO_HEIGHT=480
ID_VIDEO_FPS=29.969
ID_VIDEO_ASPECT=0.0000
ID_AUDIO_CODEC=faad
ID_AUDIO_FORMAT=mp4a
ID_AUDIO_BITRATE=125424
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
ID_LENGTH=60.33
ID_VIDEO_CODEC=ffh264

Details of the output file (MP4) using mp4info

Code:

$ mp4info myfile.mp4
mp4info version 1.4.1
myfile.mp4:
Track   Type    Info
1       video   H264 High @5.1, 60.329 secs, 1002 kbps, 640x480 @ 29.935852 fps
2       audio   MPEG-4 AAC LC, 60.501 secs, 125 kbps, 48000 Hz

cato4liberty · 02-06-2006, 12:09 PM

If anyone has suggestions for improvement, please do share your thoughts. I am curious about any options or settings to improve the quality or reduce the conversion time.