[FFmpeg-user] Best way for converting HD 1080i to DVCPRO25 DV?

[Iban Garcia]

Hi,

I go on with searching the best way to convert HD-1080i content to SD-576i
content, with losing the minimun detail... :-O

Well... I have making some new tests... but when transcoding from HD 1080i
to SD-PAL the video loses a lot of detail (i.e., 720x576i video is a little
bit blurred)

I have tested with this option UNSHARP filter in order to get a SHARPer SD
content: $comando="ffmpeg -y -threads 8 -i ".$input_file.".mxf -pix_fmt
yuv411p -aspect 16:9 -vf
\"scale=720:576:interl=1,fieldorder=bff,unsharp=7:7:2.5\" -vcodec dvvideo
-map 0:v -map 0:a:2 -ac 2 ".$output_file.".dv";

But there is a problem... unsharp filter is acting with frames and not with
fields. So, the video after filtering gets a wrong output: blinking.

Is there any way to use "sharp filter" with fields and not with frames?

Many Thanks in advance!!

Iban


2012/7/4 Andy Furniss <andyqos at ukfsn.org>

> Iban Garcia wrote:
>
>> Hi Andy,
>>
>> First of all, thank you for your interest and help.
>>
>
> Hi, I re-added list cc as I don't really know what I am talking about :-)
>
>  Why DVCPRO?
>> The reason for getting an DVCPRO50 interlaced is because I need to play it
>> in a Mediaport (OMNEON) -->
>> http://www.omneon.com/**downloads/specsheets/Spec_DV_**
>> MPEG_IMX_MediaPort.pdf<http://www.omneon.com/downloads/specsheets/Spec_DV_MPEG_IMX_MediaPort.pdf>
>>
>
> OK.
>
>  I am looking for the best way to transcode 1080i (DVCPRO-Intra) to
>> DVCPRO50
>> (interlaced).
>> I think that there are two keys to achieve the best resoults in
>> transcoding:
>>   - Image scaling (http://en.wikipedia.org/wiki/**Image_scaling<http://en.wikipedia.org/wiki/Image_scaling>
>> )
>>   - Unsharping after down-scaling
>>
>
> I see googling around, that final unsharp and prefiltering high frequency
> before the scale is the way people downsize photos.
>
> I think there will be a problem if you unsharp a weaved frame, so I guess
> you'll need to try and work with fields if that's possible.
>
> You should also keep in mind what I said about sharp interlace - you don't
> really want to have fine detail that only appears in one field or you run
> the risk of getting twitter.
>
> I am not familiar enough with ffmpeg to give direct examples, or even know
> all that's available. Maybe someone else knows how to soften before scaling.
>
>
>> DVCPRO is bff, but... fieldorder=tff is a way to get after transcoding, a
>> dvcpro with the correct fieldorder. I remember that if I set up
>> "fieldorder=bff" the fields played in a bad way.
>>
>> For now, I am looking for the best command to get it, something like this,
>> but with good parameters ;-):
>> #-----------------------------****----------------------------**--**
>> -----------------------
>>      $comand="ffmpeg -y -threads 8 -i ".$input_file.".mxf -pix_fmt
>> yuv422p -aspect 16:9 -vf \"scale=720:576:interl=1,****fieldorder=tff\"
>> -sws_flags lanczos -vcodec dvvideo -an ".$output_file.".dv";
>> #-----------------------------****----------------------------**
>> --**----------------------
>>
>
> For some reason I see the opposite to you - I have a tff source and if I
> encode with fieldorder=tff I get a dv that ffplay or mplayer assumes is bff
> - so any field rate deinterlace will judder unless I override (mplayer)
> with field-dominance 0.
>
> However if I encode it with fieldorder=bff then it really does seem to
> produce bff weave, so things work by default and specifying field-dominance
> 0 produces the wrong output.
>
>
>