[gmail] Re: Change aspect ratio without transcoding?
martijn at iphion.nl
Tue Apr 10 02:39:20 PDT 2012
On 10-04-12 10:50, Marc Leeman wrote:
>>>> I have a feeling that I'm on the wrong track here, but I'm going to ask
>>>> I have a MPEG-TS, containing H.264 video, in 4:3 aspect ratio. I'd like to
>>>> stretch the video to 16:9. Is that possible without transcoding, perhaps
>>>> by only remuxing?
>>> Hi, I don't know of any element that could do that on encoded video, but
>>> you could make an element yourself that only changes the
>> Yes, I have been researching a way to do this.
>> Using the information from , I should theoretically be able to replace
>> (using some for of 'binary sed') a certain byte sequence in the stream to
>> get what I want. The problem was, that I haven't been able to find the
>> sequence header ('000001B3') in the stream I was working on, so I gave it up.
>>  http://dvd.sourceforge.net/dvdinfo/mpeghdrs.html
> Looks like something that could be appended to the parser; that one
> should search for the correct headers.
> It might be that your stream was not properly formatted, in some cases,
> the parser corrects this.
Another thing is, that I am not a C programmer, so writing my own or
adapting an existing plugin would not be doable for me.
If someone else want to see how feasable this would be, what I was trying
to do was the following:
- find a sequence header, identified by 000001B3 byte sequence
- within the sequence header, change the 4th byte. The highest 4 bits
represent the aspect ratio, where value of '2' means '4:3' and '3' means
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