[FFmpeg-devel] Decoding AVCHD using multi-threaded code

Robert Krüger krueger
Fri Dec 19 13:59:40 CET 2008


Alexander Strange wrote:
> On Dec 17, 2008, at 9:20 AM, Michael Niedermayer wrote:
>> On Wed, Dec 17, 2008 at 11:11:09AM +0100, Jean-Michel Pour? wrote:
>>> Dear Friends,
>>> Are there any chances to parallelize decoding of this AVCHD file:
>>> http://www.kdenlive.org/videos/avchd-test-1.mts
>>> This is a typical camcorder file.
>>> Do you see any hope to parallelize or should be drop official AVCHD
>>> support in Kdenlive until multi-threading comes along?
>> The file only contains 1 slice per field, thus there is no hope to  
>> decode any
>> slices in parallel, unless 2 fields where decoded at once.
>> Decoding several fields and frames at once is being worked on.
>> Sadly ive not seem much activity there. If you care about it,
>> contact Alexander Strange. (if you provide some manpower (developers),
>> patches or (money to alexander) maybe things will move quicker)
> I tried to work on it during school, but I never had enough free time.  
> I'm on break now and working on it again.
> ffdshow-mt testers found a few decoding errors which I've fixed, but I  
> could still use more AVCHD streams for testing - I only have x264 to  
> generate stuff with.
> Beyond that, I just need more time to work on it.
> In the meantime, what are you doing the decoding for? For rendering,  
> it would definitely help, but not if you're seeking around a lot  
> during editing.
> And you should definitely look into proxy editing; AVCHD isn't an  
> intra format, so transcoding into something else will be more pleasant  
> to work with no matter how fast it is.
I could provide AVCHD Samples from Sony HDR-CX6 (1080i, in fact, I
uploaded one for issue 475,
https://roundup.mplayerhq.hu/roundup/ffmpeg/issue475) and Canon HF100
(1080i and 1080p with progressive segmented frame, which might be
another problematic case but I'm not qualified to make that call).

Let me know if that would help you and if I should upload these samples
to the ffmpeg ftp server or provide a download on our website.



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