[FFmpeg-user] ffmpeg h.264 long gop encoding and interlaced encoding

[Henk Schoneveld]

Sent from my iPod

On 19 mrt. 2013, at 07:49, Filippo Righi <filippo.righi at me.com> wrote:

> Hi there,
> this is my message i sent 30 days ago to ffmpeg.org
> 
> I am trying to convert a MOV video into a MP4 (progressive).
> I would like to maintain the same GOP settings codification.
> This are metadata of my video:
> fil at fil-ubuntu:~/Scrivania$ mediainfo 720p_50p_full.MOV 
> General
> Complete name : 720p_50p_full.MOV
> Format : MPEG-4
> Format profile : QuickTime
> Codec ID : qt 
> File size : 81.3 MiB
> Duration : 8s 560ms
> Overall bit rate mode : Variable
> Overall bit rate : 79.7 Mbps
> Encoded date : UTC 2013-02-15 13:08:12
> Tagged date : UTC 2013-02-15 13:08:12
> Copyright : http://www.technophil.sm
> com.apple.quicktime.make : Canon
> com.apple.quicktime.model : Canon EOS 6D
> com.apple.quicktime.author : TechnoPhil
> 
> Video
> ID : 1
> Format : AVC
> Format/Info : Advanced Video Codec
> Format profile : High at L5.1
> Format settings, CABAC : No
> Format settings, ReFrames : 1 frame
> Format settings, GOP : N=1
GOP=1 means that it is ALL keyframe/i-frame file. Such a file is only meant for editing purposses. You can cut frame-accurate. A file meant for 'playing/storing' a more efficient method is 'normally' wanted. All keyframe is very inefficient by means of compression so a longer GOP is used. The longer the GOP the potential compression gets better, at the cost of seek ability. For good seek ability I use a GOP of 2 seconds which translates for me in Europe to 50 frames. And encoding done by a quality measure and NOT by bitrate.
> Codec ID : avc1
> Codec ID/Info : Advanced Video Coding
> Duration : 8s 560ms
> Bit rate mode : Variable
> Bit rate : 78.0 Mbps
> Width : 1 280 pixels
> Height : 720 pixels
> Display aspect ratio : 16:9
> Frame rate mode : Constant
> Frame rate : 50.000 fps
> Color space : YUV
> Chroma subsampling : 4:2:0
> Bit depth : 8 bits
> Scan type : Progressive
> Bits/(Pixel*Frame) : 1.693
> Stream size : 79.6 MiB (98%)
> Language : English
> Encoded date : UTC 2013-02-15 13:08:12
> Tagged date : UTC 2013-02-15 13:08:12
> Color primaries : BT.709
> Transfer characteristics : BT.709
> Matrix coefficients : BT.709
> 
> I am using this script:
> 
> for i in *.MOV; do newname=`basename $i .MOV`.mp4; ffmpeg -i $i -s 1280x720 -b 5000k -bt 10000k -aspect 16:9 -r 50 -vcodec libx264 -ac 2 -ar 48000 -ab 256k -threads 4 $newname; done
> 
> The result is:
> 
> fil at fil-ubuntu:~/Scrivania$ mediainfo 720p_50p_full.mp4 
> General
> Complete name : 720p_50p_full.mp4
> Format : MPEG-4
> Format profile : Base Media
> Codec ID : isom
> File size : 5.29 MiB
> Duration : 8s 576ms
> Overall bit rate : 5 170 Kbps
> Encoded date : UTC 2013-02-15 13:08:12
> Tagged date : UTC 2013-02-15 13:08:12
> Writing application : Lavf53.21.1
> 
> Video
> ID : 1
> Format : AVC
> Format/Info : Advanced Video Codec
> Format profile : Main at L3.2
> Format settings, CABAC : Yes
> Format settings, ReFrames : 3 frames
> Codec ID : avc1
> Codec ID/Info : Advanced Video Coding
> Duration : 8s 560ms
> Bit rate : 5 000 Kbps
> Width : 1 280 pixels
> Height : 720 pixels
> Display aspect ratio : 16:9
> Frame rate mode : Constant
> Frame rate : 50.000 fps
> Color space : YUV
> Chroma subsampling : 4:2:0
> Bit depth : 8 bits
> Scan type : Progressive
> Bits/(Pixel*Frame) : 0.109
> Stream size : 5.01 MiB (95%)
> Writing library : x264 core 123 r2189 35cf912
> Encoding settings : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=4 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=0 / b_adapt=1 / b_bias=0 / direct=1 / weightb=0 / open_gop=1 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=abr / mbtree=1 / bitrate=5000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.25 / aq=1:1.00
> Language : English
> Encoded date : UTC 2013-02-15 13:08:12
> Tagged date : UTC 2013-02-15 13:08:12
> 
> How can i maintain the same GOP settings codification for both progressive and interlaced video files?
> And how can i change the "scan type" into interlaced?
> How can i change the "scan order" (Bottom Field First - Top Field First) fot interlaced encoding?
> 
> ...
> Complete name : 109G0135_01_1080i.MP4
> Format : MPEG-4
> Commercial name : XDCAM EX 35
> Format profile : Base Media / Version 2
> Codec ID : mp42
> File size : 59.2 MiB
> Duration : 13s 920ms
> Overall bit rate mode : Variable
> Overall bit rate : 35.7 Mbps
> Encoded date : UTC 2012-01-21 23:51:10
> Tagged date : UTC 2012-01-21 23:51:10
> 
> Video
> ID : 1
> Format : MPEG Video
> Commercial name : XDCAM EX 35
> Format version : Version 2
> Format profile : Main at High
> Format settings, BVOP : Yes
> Format settings, Matrix : Custom
> Format settings, GOP : M=3, N=12
> Codec ID : 61
> Duration : 13s 920ms
> Bit rate mode : Variable
> Bit rate : 34.0 Mbps
> Maximum bit rate : 35.0 Mbps
> Width : 1 920 pixels
> Height : 1 080 pixels
> Display aspect ratio : 16:9
> Frame rate mode : Constant
> Frame rate : 25.000 fps
> Color space : YUV
> Chroma subsampling : 4:2:0
> Bit depth : 8 bits
> Scan type : Interlaced
> Scan order : Top Field First
> Compression mode : Lossy
> ...
> 
> Best regards.
> Filippo
> --
> Dr. Filippo Righi
> www.technophil.sm
> 
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