[FFmpeg-user] container for yuv

[Dave Rice]

On Dec 20, 2011, at 10:17 AM, Donald McLachlan wrote:

> On 20/12/2011 9:35 AM, Dave Rice wrote:
>> 
>> On Dec 20, 2011, at 9:29 AM, Donald McLachlan wrote:
>> 
>>> Hi All,
>>> 
>>> I'm not a video guy so please bear with me if I get some terminology not quite right.
>>> 
>>> I was asked to convert a 4K video to YUV. So I used:
>> The request doesn't really provide enough information. 4K is a vague reference to frame size while YUV is a colorspace. It may be that your 4K file is already in YUV. If not then you could convert it to yuv using the -pix_fmt option.
>> 
>>>    ffmpeg -i inputFile.mp4 -f rawvideo outputFile.yuv
>>> 
>>> Because the output file is raw video without a container, players like mplayer cannot play this file without being given the frame size etc. on the command line.
>>> 
>>> I was pointed to YUV4MPEG2 http://wiki.multimedia.cx/index.php?title=YUV4MPEG2
>>> I looked at the output of ffmpeg -codecs, but I did not see anything that looks like this, nor did I see anything that (to me) says it can put YUV into a container.
>> yuv4mpeg2 is a format rather than a codec
>> Try
>> ffmpeg -i inputFile.mp4 -pix_fmt yuv420p -f yuv4mpegpipe outputFile.y4m
>> 
>> If yuv420p is not appropriate use the correct pixel format for the situation. Also note that this command doesn't change the frame size so your output will still be 4K if the input is 4K.
>> Dave Rice
> 
> Hi Dave,
> 
> I did not think the resolution of the video mattered, but I included it just in case.  Our goal is to have a file that requires minimal processing at playback time so were will to trade filesize versus cpu.

If you store a 4K resolution file uncompressed you're likely to hit your disk speed as a bottleneck. If the source is 4096×3112, that's 12,746,752 pixels, since you're likely using yuv420p that 19,120,128 bytes per frame. At 29.97 that's 4.2694 Gb per second. Most hard drives can't output data that fast.

> I had checked -pix_fmts and -codecs, but I did not know to check -formats.

Try ffmpeg -formats.
Dave Rice

> As I said, I'm not a video guy. Thanks.  It works for us.  Here is the header output of ffmpeg from a sample file we are using for in house testing.
> 
> ffmpeg -i 'Lupe (4k resolution).mp4' -f yuv4mpegpipe Lupe4k.y4m
> ffmpeg version 0.8, Copyright (c) 2000-2011 the FFmpeg developers
>   built on Nov 30 2011 13:01:22 with gcc 4.5.1 20101208 [gcc-4_5-branch revision 167585]
>   configuration: 
>   libavutil    51.  9. 1 / 51.  9. 1
>   libavcodec   53.  7. 0 / 53.  7. 0
>   libavformat  53.  4. 0 / 53.  4. 0
>   libavdevice  53.  1. 1 / 53.  1. 1
>   libavfilter   2. 23. 0 /  2. 23. 0
>   libswscale    2.  0. 0 /  2.  0. 0
> 
> Seems stream 1 codec frame rate differs from container frame rate: 47.95 (5994/125) -> 23.98 (24000/1001)
> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Lupe (4k resolution).mp4':
>   Metadata:
>     major_brand     : mp42
>     minor_version   : 0
>     compatible_brands: isomavc1mp42
>     creation_time   : 2010-07-17 23:35:29
>     title           : Lupe (4k resolution)
>   Duration: 00:02:39.70, start: 0.000000, bitrate: 18790 kb/s
>     Stream #0.0(und): Audio: aac, 48000 Hz, stereo, s16, 122 kb/s
>     Metadata:
>       creation_time   : 2010-07-17 23:35:29
>     Stream #0.1(und): Video: h264 (High), yuv420p, 4096x2304 [PAR 1:1 DAR 16:9], 18665 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95       tbc
>     Metadata:
>       creation_time   : 2010-07-17 23:35:29
> [buffer @ 0x1264c00] w:4096 h:2304 pixfmt:yuv420p tb:1/1000000 sar:1/1 sws_param:
> Output #0, yuv4mpegpipe, to 'Lupe4k.y4m':
>   Metadata:
>     major_brand     : mp42
>     minor_version   : 0
>     compatible_brands: isomavc1mp42
>     creation_time   : 2010-07-17 23:35:29
>     title           : Lupe (4k resolution)
>     encoder         : Lavf53.4.0
>     Stream #0.0(und): Video: rawvideo, yuv420p, 4096x2304 [PAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 90k tbn, 23.98 tbc
>     Metadata:
>       creation_time   : 2010-07-17 23:35:29
> Stream mapping:
>   Stream #0.1 -> #0.0
> Press [q] to stop, [?] for help
> 
> Thanks again,
> Don
>