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• Small pieces of video splitted by ffmpeg are not playing or playing with artifacts

  14 novembre 2011, par Rnd_d

  I'm trying to cut video file into small parts (0.5-5 secs) and encode these parts to h.264/aac with ffmepg. I'm using this cmd :

  ffmpeg -i 1.avi -ss 00:05:00 -t 00:00:01,50 -vcodec libx264 -threads 0
  -vpre default -acodec libfaac out1.mp4

  in vlc, some pieces are plaing without video, sound only, other pieces had a video artifacts like this screenshot.

  Maybe i didn't use some necessary agruments for ffmpeg ?

• ffmpeg : create a video from images

  8 novembre 2012, par vailen

  Is it possible to use ffmpeg create a video from a set of sequences, where the number does not start from zero ?

  For example, I have some images [test_100.jpg, test_101.jpg, test_102.jpg, ..., test_200.jpg], and I want to convert them to a video. I tried the following command, but it didn't work (it seems the number should start from zero) :

  ffmpeg -i test_%d.jpg -vcodec mpeg4 test.avi

  Any advise ?

• Using OpenMAX (IL ?) for audio/video decoding on Android

  14 septembre 2012, par Christopher Corsi

  Many of the newer hardware platforms running Android, in particular NVIDIA's Tegra 2, support OpenMAX for media acceleration. It's effectively impossible on today's devices to decode 720p video without this support, but the number of demuxers supported on Android are quite slim. The only public API I've been able to find has been through the MediaPlayer class in the Android SDK. There are multiple places in the Android source tree with OpenMAX related tidbits, however.

  On my device (Samsung Galaxy Tab 10.1) I've got access to hardware decoders through a multitude of OpenMAX libs in /system/lib, and it would be great to interface my video application with these. Can anyone point me to information on implementing a decoder powered by OpenMAX ? I've found the documentation from Khronos, but nothing in the way of example code or tutorials. I've already got demuxing and even software decoding taken care of (via libavcodec/libavformat), I'd just like to put hooks in to enable hardware encoding. I'm also assuming here it would be necessary to link directly to the ones available on the device, which makes it pretty lackluster in terms of portability, but it works.

  Alternatively, I'm interested in anything anyone knows about private APIs for accessing the video decoding available on Tegra 2 devices. Especially if there's a vdpau interface like what NVIDIA implements for desktop linux distributions, since there's plenty available for that - but I wasn't able to find shared libraries that indicate that support.