/// <summary>
/// validates a source against a given AVC level taking into account the source properties and the x264 settings
/// <param name="bytesPerFrame">bytesize of a single frame</param>
/// <param name="FS">frame area in pixels</param>
/// <param name="MBPS">macroblocks per second</param>
/// <param name="settings">the codec config to test</param>
/// <param name="compliantLevel">the first avc level that can be used to encode this source</param>
/// <returns>whether or not the current level is okay, if false and compliantLevel is -1,
/// the source could not be read</returns>
public bool validateAVCLevel(int hRes, int vRes, double framerate, x264Settings settings, out int compliantLevel)
{
settings = (x264Settings)settings.clone(); //Otherwise this sets it to the lowest compliant level anyway.
const int unrestricted = 15; // maybe this should be set as a global constant
compliantLevel = unrestricted;
if (settings.Level == unrestricted) // 15 = unrestricted
{
return(true);
}
int FrameSize = (int)maxFS(hRes, vRes);
int MBPS = maxBPS(hRes, vRes, framerate);
int hBlocks = macroblocks(hRes);
int vBlocks = macroblocks(vRes);
double bufferSize = pictureBufferSize(settings, bytesPerFrame(hRes, vRes));
int allowableBPS = this.getMaxMBPS(settings.Level);
int allowableFS = this.getMaxFS(settings.Level);
double dimensionRestriction = Math.Ceiling(Math.Sqrt((double)(allowableFS) * 8));
double allowableDPB = this.getMaxDPB(settings.Level);
if (allowableBPS >= MBPS && allowableFS >= FrameSize && allowableDPB >= bufferSize &&
dimensionRestriction >= hBlocks && dimensionRestriction >= vBlocks)
{
return(true);
}
else
{
while (settings.Level < unrestricted && (allowableBPS < MBPS || allowableFS < FrameSize ||
allowableDPB < bufferSize || dimensionRestriction < hBlocks || dimensionRestriction < vBlocks))
{
settings.Level = settings.Level + 1;
allowableBPS = this.getMaxMBPS(settings.Level);
allowableFS = this.getMaxFS(settings.Level);
dimensionRestriction = Math.Ceiling(Math.Sqrt((double)(allowableFS) * 8));
allowableDPB = this.getMaxDPB(settings.Level);
}
compliantLevel = settings.Level;
return(false);
}
}
/// <summary>
/// Checks a collection of x264Settings and modifies them if needed to fit within the level constraints.
/// </summary>
/// <param name="level">the level to enforce</param>
/// <param name="inputSettings">the collection of x264Settings to check</param>
/// <param name="frameSize">the size of the decoded video frame in bytes</param>
/// <returns>A compliant set of x264Settings</returns>
public x264Settings EnforceSettings(int level, x264Settings inputSettings, double frameSize, out AVCLevelEnforcementReturn enforcement)
{
x264Settings enforcedSettings = (x264Settings)inputSettings.clone();
enforcement = new AVCLevelEnforcementReturn();
enforcement.Altered = false;
enforcement.EnableP4x4mv = true;
enforcement.EnableVBVBufferSize = true;
enforcement.EnableVBVMaxRate = true;
enforcement.Panic = false;
enforcement.PanicString = "";
if (!checkP4x4(level, inputSettings))
{
enforcement.Altered = true;
enforcedSettings.P4x4mv = false;
}
if (checkP4x4Enabled(level, inputSettings))
{
enforcement.EnableP4x4mv = true;
}
else
{
enforcement.EnableP4x4mv = false;
}
// step through various options to enforce the max decoded picture buffer size
while (!this.checkMaxDPB(level, enforcedSettings, frameSize))
{
if (enforcedSettings.BFramePyramid)
{
enforcement.Altered = true;
enforcedSettings.BFramePyramid = false; // try turning off pyramid first
}
else
if (enforcedSettings.NbRefFrames > 1)
{
enforcement.Altered = true;
enforcedSettings.NbRefFrames -= 1; // try reducing the number of reference frames
}
else
if (enforcedSettings.NbBframes > 0)
{
enforcement.Altered = true;
enforcedSettings.NbBframes = 0; // try turning off B frames
}
else
{
enforcement.Panic = true;
enforcement.PanicString = "Can't force settings to conform to level (the frame size is too large)";
// reset output settings to original and set level to unrestrained
enforcedSettings = (x264Settings)inputSettings.clone();
enforcedSettings.Level = 15;
return(enforcedSettings);
}
}
// Disallow independent specification of MaxBitrate and MaxBufferSize unless Unrestrained
if (level < 15)
{
enforcement.EnableVBVMaxRate = false;
enforcedSettings.VBVMaxBitrate = -1;
enforcement.EnableVBVBufferSize = false;
enforcedSettings.VBVBufferSize = -1;
}
else
{
enforcement.EnableVBVMaxRate = true;
enforcement.EnableVBVBufferSize = true;
}
return(enforcedSettings);
}