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• How can I capture low resolution video on Android reliably across a range of devices ?

  8 décembre 2017, par MisterMat

  Hello Android video experts :)

  I am developing an Android application which allows the user to capture video and upload it to a remote server (it’s more involved than that but the rest of the app is not important). Because of the upload requirement, it is important that the video is of a reasonable size, so not super high resolution. Let’s say a max of 680x480 or 10Mb/minute. This is no problem on Apple devices.

  I have had what can only be described as a complete nightmare trying to capture video at a reasonably low bitrate reliably across a range of Android devices.

  As I understand it there are two ways of capturing video on Android :

  1) Using the Media Recorder/Camera API

  2) Using an Intent to open the cameras video capture application

  Option 1) gives the most flexibility and allows us to easily change the capture resolution. However the Android Camera API is NOT reliable across a range of devices, and I have very good information (including from someone who liaised with Google on this issue) that if you capture video using this API then it will crash on a good 50% of the devices out there. There is a reason that Zoom Camera FX uses an Intent for video capture. Zoom Camera (different app) seems to use Media Recorder, but has lots of bad reviews for video crashing or not working.

  Option 2) works well across a range of devices, as it uses the in built application on the device. The trouble is you have no control whatsoever on the resolution, there is a quality hint on the Intent but the camera app will normally ignore this. My Samsung Galaxy S3 records video by default at about 2Mb/s. This is way too high resolution. The built in application can of course change the resolution, but this relies on action by the user which is difficult to control.

  I understand that I could use a library such as ffmpeg to change the resolution of the video after capture. However this requires me to compile the library for Android, and also I have been informed that in order to legally use the decode/encode codecs on the device you have to pay license fees that amount to about $1 per copy of the app. Since this app will be free to use, this is not an option.

  So that’s where I’m at. I’ve searched long and high for answers, but I can’t figure out how to capture low resolution video reliably using Android.

  Any help very much appreciated !

  Matthew

• lavc/vp8 : Support resolution changes in the VP8 decoder hwaccel

  30 novembre 2017, par Jun Zhao

  lavc/vp8 : Support resolution changes in the VP8 decoder hwaccel
  Use the following command to reproduce this issue :
  
  make fate-vp8-size-change HWACCEL="vaapi -vaapi_device \
  
  /dev/dri/renderD128 -hwaccel_output_format yuv420p"
  
  SAMPLES=../fate-suite/.
  At the same time, reconstruct the public logic as a function.
  Signed-off-by : Yun Zhou <yunx.z.zhou@intel.com>
  
  Signed-off-by : Jun Zhao <jun.zhao@intel.com>
  
  Signed-off-by : Mark Thompson <sw@jkqxz.net>
  

  • [DH] libavcodec/vp8.c

• ffmpeg scale/forcing a video resolution issue

  30 janvier 2018, par Massimo Vantaggio

  I try to be sure that the video comes out with a resolution of 1920 x1080,
  If not the encoding must force this resolution.
  I need this to create fine adaption set from a video input with standard resolution (HD).

  Im unable to get always this resolution, for example with a movie of
  1920 x 1040 i get 1993 x 1080

  , below my ffmpeg command line :

  ffmpeg -y -i $name -i logo1080.png -c:a aac -b:a 256k -ar 48000 -ac 2 -async 1 -c:v libx264 -x264opts keyint=$GOP:min-keyint=$GOP:no-scenecut -bf 0 -r $FPSC -b:v 2400k -maxrate 2400k -bufsize 1200k -profile:v main -t $FDUR -filter_complex "[0:v][1:v]overlay=main_w-overlay_w-10:10,scale=1920:1080" format1080.mp4

  I tried every possibility that the ffmpeg scale page tells, without understand how to fix it.
  I think i need some help,
  Thanks,
  Massimo