Converting SD DVPAL > H264 for iPad / iPhone advice

[wooduk]

Hello

I have around 7gb of DVPAL SD video which I need to convert to iPhone and iPad.

I need to compress it as much as possible into H264 (no more than 2gb max). I have managed to get 7gb down to 1.5gb but the quality is not great. I was looking online and found someone talking about converting the SD DVPAL 420 to AppleProRes 422 first and then do the H264 conversion as the color space could cause issues and I would get a better conversion. Is this true ?

End delivery is iPhone and iPad. I understand the iPad is 4:3 anyway so resolution of 720 x 576 is fine, but any advice if making the resolution smaller for iPhone is worth it and therefore reduce the file size further ?

Any advice would be great! Thanks!

Please see the original material and H264 formats I used so far ....

- Original Material format

General
Complete name : Z1_Day 1_Tape 6
Format : QuickTime
Format/Info : Original Apple specifications
File size : 604 MiB
Duration : 2mn 47s
Overall bit rate mode : Constant
Overall bit rate : 30.3 Mbps
Encoded date : UTC 2006-09-25 14:48:22
Tagged date : UTC 2012-10-25 21:22:00
Writing library : Apple QuickTime
Original source medium : 001
©TSC : 25
©TSZ : 1

Video
ID : 1
Format : DV
Codec ID : dvcp
Duration : 2mn 47s
Source duration : 2mn 47s
Source_Duration_FirstFrame : 34ms
Source_Duration_LastFrame : -14ms
Bit rate mode : Constant
Bit rate : 24.4 Mbps
Encoded bit rate : 28.8 Mbps
Width : 703 pixels
Original width : 720 pixels
Height : 576 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 fps
Standard : PAL
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Bottom field only
Compression mode : Lossy
Bits/(Pixel*Frame) : 2.414
Stream size : 573 MiB (95%)
Source stream size : 574 MiB (95%)
Language : English
Encoded date : UTC 2006-09-25 14:51:09
Tagged date : UTC 2006-09-25 14:51:10
Color primaries : BT.601 PAL
Transfer characteristics : BT.709
Matrix coefficients : BT.601

- H264 format I did using iFFMPEG on Mac based on above format.

General
Complete name : blah.avi
Format : MPEG-4
Format profile : Base Media
Codec ID : isom
File size : 48.4 MiB
Duration : 15mn 33s
Overall bit rate mode : Variable
Overall bit rate : 435 Kbps
Writing application : Lavf54.63.104

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3.1
Format settings, CABAC : Yes
Format settings, ReFrames : 3 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 15mn 32s
Bit rate : 302 Kbps
Nominal bit rate : 414 Kbps
Width : 720 pixels
Height : 576 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 fps
Standard : PAL
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.029
Stream size : 33.6 MiB (69%)
Writing library : x264 core 129 r481 3a1e20c
Encoding settings : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=8 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=1 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=cbr / mbtree=1 / bitrate=414 / ratetol=1.0 / qcomp=0.60 / qpmin=3 / qpmax=51 / qpstep=4 / vbv_maxrate=414 / vbv_bufsize=165 / nal_hrd=none / ip_ratio=1.41 / aq=1:1.00

[_Al_]

Install Avisynth: https://www.videohelp.com/download/Avisynth_258.exe
download QTGMC, unzip it and put content into Avisynth plugin folder: http://www.mediafire.com/download/su7l5jtcobabksk/QTGMC-3.32.zip

AviSource("D:\Your_DV.avi")
Assumebff()
QTGMC()
Lanczos4Resize(768,576)

Load that script from above, Avisynth script (create *.txt file and rename it into *.avs) into some x264 encoder like Ripbot264, Megui, staxrip, there are even different encoders with GUI more simple, look at videohelp page https://www.videohelp.com/tools/sections/video-encoders , you just have to try if it loads Avisynth script file - avs.

EDIT: I see, you have Mac, that is not going to work ....

[Cornucopia]

300kbps? Wow. That's probably why. Likely, your bitrate is too low for good quality.

As a VERY BROAD rule of thumb, your bitrates for good quality, standard SD PAL (720x576) material is gonna be in the range of:
1. 25Mbps for DV (exactly)
2. 4-8Mbps for MPEG2/DVD
3. 1.5-4Mbps for MPEG4,Part2/Divx/Xvid
4. 650kbps-2Mbps for h.264/AVC/MPEG4,Part10

So your test encode is HALF of the lowest bitrate on the list! Granted there are many, many variables that affect the outcome which can allow for lower or higher settings, but it really is no wonder that you're having trouble.

At 1Mbps, that's 7.5MB/minute. If you were to have a 2GB limit (aka 2048MB), that would allow you 273 minutes of material! But if you're starting out with 7GB of DV material, that equates to ~35 minutes, which at 1Mbps/7.5MBpm = 262MB. And I would suggest that a higher bitrate, such as 2 or 2.5Mbps would give you something very close to the quality look of your DV material, which would STILL be ~656MB - well under your 2GB limit.

That ProRes business is a red herring. Your source is 4:2:0, your target is 4:2:0, thus no need for any colorspace conversion, and should be no errors involved.

Scott

<edit> and always remember "Filesize = Bitrate * Running time", and you can always SPLIT your files (preferrably before re-encoding) into "chapter" segments that still individually conform to 2GB limits.

[wooduk]

Hi

[EDIT - uploaded a screen grab of a encoder calculator, so at 600kbps that would be 2.6GB.]

Thank you for your message.

> 300kbps? Wow. That's probably why. Likely, your bitrate is too low for good quality.

Yeh I kind of knew it was pretty low

> At 1Mbps, that's 7.5MB/minute. If you were to have a 2GB limit (aka 2048MB), that would allow you 273 minutes of material! But if you're >starting out with 7GB of DV material, that equates to ~35 minutes, which at 1Mbps/7.5MBpm = 262MB. And I would suggest that a higher >bitrate, such as 2 or 2.5Mbps would give you something very close to the quality look of your DV material, which would STILL be ~656MB - >well under your 2GB limit.

I sort of followed you there. Basically that 7gb of video turns into 482.59minutes of material (around 8 hours). So not sure I follow your 35 minutes of material. The example I sent was just one video, there are 30 in total of various format.

> That ProRes business is a red herring. Your source is 4:2:0, your target is 4:2:0, thus no need for any colorspace conversion, and should > be no errors involved.

I thought that H264 was 4:2:2 ?

<edit> and always remember "Filesize = Bitrate * Running time", and you can always SPLIT your files (preferrably before re-encoding) into "chapter" segments that still individually conform to 2GB limits.

So if I did encode 482mins of material @ 2mb thats just under 1gb ? or am I missing something.

Thanks

Paul