status_t MediaOutputInfo::CreateBufferGroup() {
bufferPeriod = ComputeBufferPeriod();
if (bufferGroup == 0) {
int32 count = int32(downstreamLatency/bufferPeriod)+2;
fprintf(stderr," downstream latency = %lld, buffer period = %lld, buffer count = %i\n",
downstreamLatency,bufferPeriod,count);
// allocate the buffers
bufferGroup = new BBufferGroup(ComputeBufferSize(),count);
if (bufferGroup == 0) {
fprintf(stderr,"<- B_NO_MEMORY\n");
return B_NO_MEMORY;
}
status_t status = bufferGroup->InitCheck();
if (status != B_OK) {
fprintf(stderr,"<- BufferGroup initialization failed\n");
BBufferGroup * group = bufferGroup;
bufferGroup = 0;
delete group;
return status;
}
}
return B_OK;
}
// returns result in # of microseconds
bigtime_t MediaOutputInfo::ComputeBufferPeriod(const media_format & format) {
bigtime_t bufferPeriod = 25*1000; // default 25 milliseconds
switch (format.type) {
case B_MEDIA_MULTISTREAM:
// given a buffer size of 8192 bytes
// and a bitrate of 1024 kilobits/millisecond (= 128 bytes/millisecond)
// we need to produce a buffer every 64 milliseconds (= every 64000 microseconds)
bufferPeriod = bigtime_t(1000.0 * 8.0 * ComputeBufferSize(format)
/ format.u.multistream.max_bit_rate);
break;
case B_MEDIA_ENCODED_VIDEO:
bufferPeriod = bigtime_t(1000.0 * 8.0 * ComputeBufferSize(format)
/ format.u.encoded_video.max_bit_rate);
break;
case B_MEDIA_ENCODED_AUDIO:
bufferPeriod = bigtime_t(1000.0 * 8.0 * ComputeBufferSize(format)
/ format.u.encoded_audio.bit_rate);
break;
case B_MEDIA_RAW_VIDEO:
// Given a field rate of 50.00 fields per second, (PAL)
// we need to generate a field/buffer
// every 1/50 of a second = 20000 microseconds.
bufferPeriod = bigtime_t(1000000.0
/ format.u.raw_video.field_rate);
break;
case B_MEDIA_RAW_AUDIO:
// Given a sample size of 4 bytes [B_AUDIO_INT]
// and a channel count of 2 and a buffer_size
// of 256 bytes and a frame_rate of 44100 Hertz (1/sec)
// 1 frame = 1 sample/channel.
// comes to ??
// this is a guess:
bufferPeriod = bigtime_t(1000000.0 * ComputeBufferSize(format)
/ (format.u.raw_audio.format
& media_raw_audio_format::B_AUDIO_SIZE_MASK)
/ format.u.raw_audio.channel_count
/ format.u.raw_audio.frame_rate);
break;
default:
break;
}
return bufferPeriod;
}
dng_simple_image::dng_simple_image (const dng_rect &bounds,
uint32 planes,
uint32 pixelType,
dng_memory_allocator &allocator)
: dng_image (bounds,
planes,
pixelType)
, fMemory ()
, fAllocator (allocator)
{
uint32 bytes =
ComputeBufferSize (pixelType, bounds.Size (), planes, pad16Bytes);
fMemory.Reset (allocator.Allocate (bytes));
fBuffer = dng_pixel_buffer (bounds, 0, planes, pixelType, pcInterleaved, fMemory->Buffer ());
}
uint32 MediaOutputInfo::ComputeBufferSize() {
return ComputeBufferSize(output.format);
}
