[FFmpeg-user] How to speed up thumbnail generation for video files using FFMPEG on MIPS

[Pavan Kulkarni]

Pardon me .. I was not clear.

> Why do you want to resolve them / which errors/warning are you
> talking about?
These errors below. I presumed they might give an idea of what's eating up
so much of time.
[h264 @ 0x443ff0] non-existing SPS 13 referenced in buffering period
[h264 @ 0x443ff0] Missing reference picture


[h264 @ 0x443ff0] decode_slice_header error


[h264 @ 0x443ff0] Missing reference picture


[h264 @ 0x443ff0] decode_slice_header error


[h264 @ 0x443ff0] Missing reference picture


[h264 @ 0x443ff0] decode_slice_header error


[h264 @ 0x443ff0] Missing reference picture


[h264 @ 0x443ff0] decode_slice_header error


[h264 @ 0x443ff0] concealing 8160 DC, 8160 AC, 8160 MV errors


[h264 @ 0x443ff0] Missing reference picture


> What about
> $ time ./ffmpeg -i Pirates_remux_short.ts thumphd.jpg
Around 14 seconds
> and
> $ time ./ffmpeg -ss 18 -i Pirates_remux_short.ts thumphd2.jpg
Around 33 seconds.

Equivalent command o/p for .mp4 files
> $ time ./ffmpeg -i input.mp4 thumphd.jpg
Around 1 second (BUT the thumbnail does not get generated. It is black)
> and
> $ time ./ffmpeg -ss 18 -i input.mp4 thumphd2.jpg
Around 27 seconds.
Please tell me if you need uncut console o/p


In the older FFMPEG version if I tried to seek without the select filter,
it produced a blank thumbnail for ..mp4 files. (It worked alright for .ts
files). With new FFMPEG build, even for .mp4 files, seek option works
WITHOUT the select filter.
In summary, with new FFMPEG build excellent quality thumbnails are produced
with seek and without the select filter. BUT there has been no improvement
in terms of time taken

What I'm trying to achieve is decent quality thumbnails for .mp4, .ts,
.mov, .3gp files within a reasonable amount of time.
Do you feel that this is as far as we can go to achieve optimal times? I'm
not an experienced mips asm developer, so I'm trying to get things working
using the existing ffmpeg libraries.


On Mon, Jul 9, 2012 at 5:03 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Pavan Kulkarni <pavanvkbgm <at> gmail.com> writes:
>
> > time ./ffmpeg -ss 18 -i Pirates_remux_short.ts  -an -s 150x100
> thumb12.jpg
>
> To elaborate (I missed the scaling in your first mail):
> libswscale does not contain optimizations for mips, so
> scaling is expensive.
> If you are an experienced mips asm developer, optimizing libswscale
> is definitely possible and many operations would gain speed,
> the alternative is to optimize the h264 decoder (which would
> also show benefits when decoding without scaling) or you
> optimize both;-)
>
> Carl Eugen
>
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>