我需要使用Xamarin.MP4Transcoder.Transcoder将视频转码为640 * 480分辨率。目前有2种可用的分辨率720pFormat和960x540Format。 Transcoder类中有一个名为Transcoder For (IMediaFormatStrategy strategy)
的方法。
我可以使用MIME类型,宽度和高度创建MediaFormat对象 通过以下提到的代码片段:
MediaFormat obj = MediaFormat.CreateVideoFormat("video/mp4", 480, 640);
但问题是如何将其分配给IMediaFormatStrategy或者是否有其他方法可以实现此目的。
Piece of code for Transcoding a video:
Xamarin.MP4Transcoder.Transcoder.For960x540Format().ConvertAsync(inputFile, outputFile, f =>
{
onProgress?.Invoke((int)(f * (double)100), 100);
} );
inputFile: Video file which needs to be transcoded.
outputFile: Resultant file generated after transcoding.
有关详细信息,请参阅https://github.com/neurospeech/xamarin-android-ffmpeg
感谢任何帮助。在此先感谢!!
答案 0 :(得分:1)
我必须做类似的事情,幸运地发现它是用Java制作的,然后我只需要将它转换为C#。
结果类(640x360)如下所示:
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// this is obsolete: MediaCodecInfo.CodecProfileLevel.AACObjectLC, so using MediaCodecProfileType.Aacobjectlc instead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;
}
}
只需将LONGER_LENGTH和SHORTER_LENGTH更改为您需要的任何分辨率,显然,为它创建一个新类。 也许还可以制作一个兼容两种长度的泛型类,但我还没有需要它。