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• How to scale the YUV image from MediaCodec output with any color format ?

  17 octobre 2014, par Frank Bush

  I’m using MediaCodec to decode the video and using sws_scale(from ffmpeg) to rescale it.I can deal with one special color format,eg. YUV420P, and rescale it to destination size. But I have to do some preparing work, such as getting the linesize and memcpy the output buffer to three plain slices(data[0],data[1],data[2]).And the decoder output color format varies on different devices.If I get the colorformat,is there a method in ffmpeg to rescale it automatically without special dealing(Of course, the color format should be supported by ffmpeg) ?

• How to (properly) use the ExtendRtspStream command in Google's Nest Device Access API ?

  19 juillet 2021, par 6twenty

  Using Google's Nest Device Access API, I can generate an RTSP camera stream using the GenerateRtspStream command and subsequently stop the stream using the StopRtspStream command. Makes sense, however these streams are only alive for 5 minutes by default - so the API also features another command : ExtendRtspStream.

  


  On the face of it, this sounds like it should "extend" the stream you had originally created, however these RTSP stream urls include an auth query parameter and extending a stream simply issues a new token to use for this, which means that the url for the stream changes every time it gets extended. So in reality the stream isn't getting extended at all as the url you use to access the stream still gets invalidated, and you have to restart it with a new url to continue watching the stream. So what's the point ? You may as well just call the GenerateRtspStream command and switch over to that one once the first expires. Is there some way to seamlessly change the RTSP url mid-stream that I'm not aware of using FFMPEG, perhaps ? Or to have a proxy server that broadcasts a static RTSP url and seamlessly switches the actual url each time it gets extended ?

  


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  Rant starts here : I'm really hoping that this behaviour is actually a bug or oversight in the design of the API, and that ExtendRtspStream is supposed to keep the same url alive for as long as needed, because it's awfully pointless to have an RTSP stream that only stays alive for a max of 5 minutes. Heck, it'd be more useful to have an API that just returns the latest single-image snapshot from the camera every 10 seconds or so - but alas, there's no API for that either.

  


• FFMPEG Wrong color space with ProRes 4444 [closed]

  6 février 2020, par Mirza Kadic

  I’m unable to convert a video with ffmpeg in codec ProRes 4444 without color shift (something to do with colorspace). If I do quicktime png, color space stays the same, no problems with that.
  The only thing that fixes this is -vf colormatrix=bt601:bt709, but then I loose alpha channel, which I need of course.
  Any help would be appreciated.