Je devais faire la même chose, et heureusement trouvé comment il a été fait en Java, et puis j'ai juste dû le convertir en C#.
La classe résultante (pour 640x360) ressemble à ceci:
public class For640x360Format : Java.Lang.Object, IMediaFormatStrategy
{
public static int AUDIO_BITRATE_AS_IS = -1;
public static int AUDIO_CHANNELS_AS_IS = -1;
static String TAG = "640x360FormatStrategy";
static int LONGER_LENGTH = 640;
static int SHORTER_LENGTH = 360;
static int DEFAULT_VIDEO_BITRATE = 8000 * 1000; // From Nexus 4 Camera in 720p
int mVideoBitrate;
int mAudioBitrate;
int mAudioChannels;
public For640x360Format()
{
mVideoBitrate = DEFAULT_VIDEO_BITRATE;
mAudioBitrate = AUDIO_BITRATE_AS_IS;
mAudioChannels = AUDIO_CHANNELS_AS_IS;
}
public For640x360Format (int videoBitrate)
{
mVideoBitrate = videoBitrate;
mAudioBitrate = AUDIO_BITRATE_AS_IS;
mAudioChannels = AUDIO_CHANNELS_AS_IS;
}
public For640x360Format (int videoBitrate, int audioBitrate, int audioChannels)
{
mVideoBitrate = videoBitrate;
mAudioBitrate = audioBitrate;
mAudioChannels = audioChannels;
}
public MediaFormat CreateAudioOutputFormat (MediaFormat inputFormat)
{
if (mAudioBitrate == AUDIO_BITRATE_AS_IS || mAudioChannels == AUDIO_CHANNELS_AS_IS) return null;
// Use original sample rate, as resampling is not supported yet.
MediaFormat format = MediaFormat.CreateAudioFormat (MediaFormatExtraConstants.MimetypeAudioAac,
inputFormat.GetInteger (MediaFormat.KeySampleRate),
mAudioChannels);
// this is obsolete: MediaCodecInfo.CodecProfileLevel.AACObjectLC, so using MediaCodecProfileType.Aacobjectlc instead
format.SetInteger (MediaFormat.KeyAacProfile, (int)MediaCodecProfileType.Aacobjectlc);
format.SetInteger (MediaFormat.KeyBitRate, mAudioBitrate);
return format;
}
public MediaFormat CreateVideoOutputFormat (MediaFormat inputFormat)
{
int width = inputFormat.GetInteger (MediaFormat.KeyWidth);
int height = inputFormat.GetInteger (MediaFormat.KeyHeight);
int longer, shorter, outWidth, outHeight;
if (width >= height)
{
longer = width;
shorter = height;
outWidth = LONGER_LENGTH;
outHeight = SHORTER_LENGTH;
}
else
{
shorter = width;
longer = height;
outWidth = SHORTER_LENGTH;
outHeight = LONGER_LENGTH;
}
if (longer * 9 != shorter * 16)
{
throw new OutputFormatUnavailableException ("This video is not 16:9, and is not able to transcode. (" + width + "x" + height + ")");
}
if (shorter <= SHORTER_LENGTH)
{
#if DEBUG
Console.WriteLine ("This video is less or equal to 720p, pass-through. (" + width + "x" + height + ")");
#endif
return null;
}
MediaFormat format = MediaFormat.CreateVideoFormat ("video/avc", outWidth, outHeight);
format.SetInteger (MediaFormat.KeyBitRate, mVideoBitrate);
format.SetInteger (MediaFormat.KeyFrameRate, 30);
format.SetInteger (MediaFormat.KeyIFrameInterval, 3);
// this is obsolete: MediaCodecInfo.CodecCapabilities.COLORFormatSurface, so using MediaCodecCapabilities.Formatsurface instead
format.SetInteger (MediaFormat.KeyColorFormat, (int)MediaCodecCapabilities.Formatsurface);
return format;
}
}
changer juste LONGER_LENGTH et SHORTER_LENGTH à ce que la résolution dont vous avez besoin et, de toute évidence, créer une nouvelle classe pour elle. Pourrait probablement aussi juste faire une classe générique qui prend dans les deux longueurs, mais je n'ai pas encore eu besoin de lui.
Link to the Java code