Hi,
I am having a problem with reading video files with the ffmpeg api. I am
building on a python wrapper, that someone else wrote. I noticed a bug,
but the creator could not solve the issue. So I am trying to hunt it
down by myself.
The problem is that the wrapper truncates any video I tried it with.
The basic idea of the wrapper is, to use
av_read_frame()
to read frames until it returns a value < 0. That seems to work, and I
get the right frames back all the time (even using seek of the wrapper),
except for the last frames. It seems as av_read_frame only reads until
the last key frame and does not go beyond it.
FFMPEG command line tools, on the other hand, can extract the full video
sequence and do not omit anything.
I am not sure whether the information I give here is enough to start
hunting down the bug. I am not experienced at all with the ffmpeg api
and I am working with the code I have got from the other guy. Let me
know if you need something else to start tracing the problem.
Thanks,
Peter
Stuff to test the problem:
Wrapper code with line calling av_read_frame:
===========================
https://bitbucket.org/groakat/ffvideo/src/b45143f755ac8da1e6ed4f52a11217af1e093d54/ffvideo/ffvideo.pyx?at=default#cl-231
( you can install the wraper with pip install
https://bitbucket.org/groakat/ffvideo/get/b45143f755ac.zip)
Rendered test Video (1000 frames numbered from 1..1000):
====================================
https://www.dropbox.com/s/guu33jyy4t7sq53/test.avi?dl=0
Script to generate the video:
=================
First generate frames:
#!/bin/bash
for i in $(seq -f "%05g" 1 1000)
do
convert -size 51x18 -pointsize 16 -font
/usr/share/fonts/truetype/freefont/FreeMono.ttf label:$i $i.png
done
Then use to create a video from the image sequence:
ffmpeg -y -f image2 -r 30 -i "%05d.png" -r 30 test.avi
Then test whether ffmpeg can read all frames:
ffmpeg -i "test.avi" -an -f image2 "output_%05d.png"
Python script using the wrapper from above to extract the frames:
========================================
from ffvideo import VideoStream
from scipy.misc import imsave
vs = VideoStream('test.avi', exact_seek=True)
cnt = 0
for frame in vs:
f = frame.ndarray()
imsave("frame {0:05d}.png".format(cnt), f)
cnt += 1
My ffmpeg version
===========
$ ffmpeg
ffmpeg version 2.2.git Copyright (c) 2000-2014 the FFmpeg developers
built on Apr 9 2014 16:32:16 with gcc 4.8 (Ubuntu/Linaro
4.8.1-10ubuntu9)
configuration: --prefix=/home/peter/ffmpeg_build
--extra-cflags=-I/home/peter/ffmpeg_build/include
--extra-ldflags=-L/home/peter/ffmpeg_build/lib --bindir=/home/peter/bin
--extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac
--enable-libfreetype --enable-libmp3lame --enable-libopus
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-x11grab --enable-shared
WARNING: library configuration mismatch
avutil configuration: --enable-gpl --enable-libmp3lame
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-shared
avcodec configuration: --enable-gpl --enable-libmp3lame
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-shared
avformat configuration: --enable-gpl --enable-libmp3lame
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-shared
avdevice configuration: --enable-gpl --enable-libmp3lame
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-shared
avfilter configuration: --enable-gpl --enable-libmp3lame
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-shared
swscale configuration: --enable-gpl --enable-libmp3lame
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-shared
swresample configuration: --enable-gpl --enable-libmp3lame
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-shared
postproc configuration: --enable-gpl --enable-libmp3lame
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-nonfree --enable-shared
libavutil 52. 74.100 / 52. 75.100
libavcodec 55. 58.102 / 55. 58.103
libavformat 55. 36.102 / 55. 36.102
libavdevice 55. 11.100 / 55. 11.100
libavfilter 4. 3.100 / 4. 3.100
libswscale 2. 6.100 / 2. 6.100
libswresample 0. 18.100 / 0. 18.100
libpostproc 52. 3.100 / 52. 3.100
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile
options] outfile}...
Use -h to get full help or, even better, run 'man ffmpeg'
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