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• av1/h264_metadata, filter_units : Count down when deleting units

  17 juin 2019, par Andreas Rheinhardt

  av1/h264_metadata, filter_units : Count down when deleting units
  When testing whether a particular unit should be kept or discarded, it
  
  is best to start at the very last unit of a fragment and count down,
  
  because that way a unit that will eventually be deleted won't be
  
  memmoved during earlier deletions ; and frag/au->nb_units need only be
  
  evaluated once in this case and the counter is automatically correct
  
  when a unit got deleted.
  It also works for double loops, i.e. when looping over all SEI messages
  
  in all SEI units of an access unit.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/av1_metadata_bsf.c
  • [DH] libavcodec/filter_units_bsf.c
  • [DH] libavcodec/h264_metadata_bsf.c

• truehd_core : Miscellaneous improvements

  6 juillet 2019, par Andreas Rheinhardt

  truehd_core : Miscellaneous improvements
  1. The loop counter of the substream_directory loop is always less than
  
  the number of substreams, yet within the loop it is checked whether it
  
  is less than FFMIN(3, s->hdr.num_substreams), although the check for < 3
  
  would suffice.
  
  2. In case the packet is a major sync packet, the last two bytes of the
  
  major sync structure were initialized to 0xff and then immediately
  
  overwritten afterwards without ever making use of the values just set.
  
  3. When updating the parity_nibble during writing the new
  
  substream_directory, the parity_nibble is updated one byte at a time
  
  with bytes that might be read from the output packet's data. But one can
  
  do both bytes at the same time without resorting to the data just
  
  written by XOR'ing with the variable that contains the value that has
  
  just been written as a big endian number. This changes the intermediate
  
  value of parity_nibble, but in the end it just amounts to a reordering
  
  of the sum modulo two that will eventually be written as parity_nibble.
  
  Due to associativity and commutativity, this value is unchanged.
  
  4. init_get_bits8 already checks that no overflow happens during the
  
  conversion of its argument from bytes to bits. ff_mlp_read_major_sync
  
  makes sure not to overread (the maximum size of a major_sync_info is 60
  
  bytes anyway) and last_offset is < 2^13, so that no overflow in the
  
  calculation of size can happen, i.e. the check for whether size is >= 0
  
  is unnecessary. But then size is completely unnecessary and can be
  
  removed.
  
  5. In case the packet is just passed through, it is unnecessary to read
  
  the packet's dts. This is therefore postponed to when we know that the
  
  packet is not passed through.
  
  6. Given that it seems overkill to use a bitreader just for one
  
  variable, the size of the input access unit is now read directly.
  
  7. A substream's offset (of the end of the substream) is now stored as is
  
  (i.e. in units of words).
  These changes amount to a slight performance improvement : It improved
  
  from 5897 decicycles of ten runs with about 262144 runs each (including
  
  an insignificant amount — about 20-25 usually of skips) to 5747
  
  decicycles under the same conditions.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/truehd_core_bsf.c

• How to convert bitmaps array to a video in Android ?

  12 juillet 2020, par Kamran Janjua

  I have a buffer which is filled with image bitmaps as they arrive (using a thread to continuously take pictures). I would then like to dump that bitmap buffer (I have a hashmap at the moment for matching the keys) into a .mp4 file.

  


  Here is the code to continuously capture the images using a handler.

  


  button.setOnClickListener {
 prepareUIForCapture()
 if(isRunning){
   handler.removeCallbacksAndMessages(null)
   Logd("Length of wide: " + MainActivity.wideBitmaps.size)
   Logd("Length of normal: " + MainActivity.normalBitmaps.size)
   // This is where the make video would be called => makeVideoFootage()
   restartActivity()
 }else{
    button.text = "Stop"
    handler.postDelayed(object : Runnable {
    override fun run(){
       twoLens.reset()
       twoLens.isTwoLensShot = true
       MainActivity.cameraParams.get(dualCamLogicalId).let {
                if (it?.isOpen == true) {
                Logd("In onClick. Taking Dual Cam Photo on logical camera: " + dualCamLogicalId)
                takePicture(this@MainActivity, it)
                Toast.makeText(applicationContext, "Captured", Toast.LENGTH_LONG).show()
                            }
                        }
                        handler.postDelayed(this, 1000)
                    }
                }, 1000)
            }
            isRunning = !isRunning
        }


  


  This takes picture every 1 second until the stop button is pressed. Here is the function that retrieves the images and saves them into a hashmap.

  


  val wideBuffer: ByteBuffer? = twoLens.wideImage!!.planes[0].buffer
val wideBytes = ByteArray(wideBuffer!!.remaining())
wideBuffer.get(wideBytes)

val normalBuffer: ByteBuffer? = twoLens.normalImage!!.planes[0].buffer
val normalBytes = ByteArray(normalBuffer!!.remaining())
normalBuffer.get(normalBytes)

val tempWideBitmap = BitmapFactory.decodeByteArray(wideBytes, 0, wideBytes.size, null)
val tempNormalBitmap = BitmapFactory.decodeByteArray(normalBytes, 0, normalBytes.size, null)
MainActivity.counter += 1
MainActivity.wideBitmaps.put(MainActivity.counter.toString(), tempWideBitmap)
MainActivity.normalBitmaps.put(MainActivity.counter.toString(), tempNormalBitmap)


  


  counter is used to match the frames and that is why I am using a hashmap instead of an array. I have complied the ffmpeg as follows.

  


  implementation 'com.writingminds:FFmpegAndroid:0.3.2'



  


  Is this the correct way ?
I would appreciate some starter code in makeVideoFootage().

  


  fun makeVideoFootage(){
// I would like to get the bitmaps from MainActivity.wideBitmaps and then dump them into a video wide.mp4.
}


  


  Any help regarding this would be appreciated.

  


  P.S. I have read the existing questions and their answers (running from the command line), but I do not know how to proceed.