Flutter视频编码配置插件h264_profile_level_id的使用
Flutter视频编码配置插件h264_profile_level_id的使用
h264_profile_level_id
是一个用于处理H.264 profile-level-id
值的Dart工具,基于Google的libwebrtc C++代码。它提供了多种功能来解析、生成和比较H.264的Profile和Level信息。下面我们将详细介绍如何使用这个插件,并提供一个完整的示例demo。
1. API介绍
h264_profile_level_id
提供了以下API:
-
H264 Profile标识符:
ProfileConstrainedBaseline
ProfileBaseline
ProfileMain
ProfileConstrainedHigh
ProfileHigh
-
H264 Level标识符:
Level1_b
,Level1
,Level1_1
,Level1_2
,Level1_3
Level2
,Level2_1
,Level2_2
Level3
,Level3_1
,Level3_2
Level4
,Level4_1
,Level4_2
Level5
,Level5_1
,Level5_2
-
函数:
parseProfileLevelId(str)
:解析表示为3个十六进制字节字符串的profile-level-id
。profileLevelIdToString(profile_level_id)
:返回profile-level-id
的规范字符串表示(3个十六进制字节),或对于无效的profile-level-id
返回null。parseSdpProfileLevelId(params)
:解析SDP键值对中表示为3个十六进制字节字符串的profile-level-id
。isSameProfile(params1, params2)
:检查两个参数对象是否具有相同的H.264 Profile。generateProfileLevelIdForAnswer(local_supported_params, remote_offered_params)
:根据本地支持的参数和远程提供的参数生成适合SDP协商的profile-level-id
。
-
类:
ProfileLevelId
:包含H.264的Profile和Level信息。
2. 示例代码
下面是一个完整的示例demo,展示了如何使用h264_profile_level_id
插件来处理H.264的profile-level-id
。
import 'package:h264_profile_level_id/h264_profile_level_id.dart';
void main() {
// 创建一个ProfileLevelId实例
final ProfileLevelId profileLevelId = ProfileLevelId(
profile: H264Utils.ProfileMain, // 设置Profile为Main
level: H264Utils.Level3_1, // 设置Level为3.1
);
// 打印Profile和Level
print('profile: ${profileLevelId.profile}, level: ${profileLevelId.level}');
// 输出: profile: 3, level: 31
// 将ProfileLevelId转换为字符串
String? profileLevelIdString = H264Utils.profileLevelIdToString(profileLevelId);
print('profile-level-id string: $profileLevelIdString');
// 输出: profile-level-id string: 4d0301
// 解析字符串为ProfileLevelId
String inputStr = '4d0301'; // Main Profile, Level 3.1
ProfileLevelId? parsedProfileLevelId = H264Utils.parseProfileLevelId(inputStr);
if (parsedProfileLevelId != null) {
print('Parsed profile: ${parsedProfileLevelId.profile}, level: ${parsedProfileLevelId.level}');
// 输出: Parsed profile: 3, level: 31
} else {
print('Invalid profile-level-id string');
}
// 检查两个Codec参数对象是否具有相同的Profile
Map<String, dynamic> params1 = {'profile-level-id': '4d0301'};
Map<String, dynamic> params2 = {'profile-level-id': '4d0301'};
bool isSame = H264Utils.isSameProfile(params1, params2);
print('Is same profile: $isSame');
// 输出: Is same profile: true
// 生成适合SDP协商的profile-level-id
Map<String, dynamic> localSupportedParams = {'profile-level-id': '4d0301'};
Map<String, dynamic> remoteOfferedParams = {'profile-level-id': '4d0301'};
String? generatedProfileLevelId = H264Utils.generateProfileLevelIdForAnswer(localSupportedParams, remoteOfferedParams);
print('Generated profile-level-id for SDP answer: $generatedProfileLevelId');
// 输出: Generated profile-level-id for SDP answer: 4d0301
}
更多关于Flutter视频编码配置插件h264_profile_level_id的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html
更多关于Flutter视频编码配置插件h264_profile_level_id的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html
在Flutter中,如果你需要配置视频编码参数,特别是H.264编码的profile_level_id
,通常会涉及到调用原生平台(iOS和Android)的编码库。Flutter本身不提供直接的视频编码功能,但你可以通过插件来访问这些功能。
以下是一个基本的示例,展示如何通过Flutter插件来配置H.264编码的profile_level_id
。这里我们假设你已经有一个可以访问原生视频编码功能的Flutter插件。
1. 创建Flutter插件
首先,你需要创建一个Flutter插件来封装原生平台的功能。这里假设你已经有一个Flutter插件项目。
iOS部分
在ios/Classes
目录下创建一个Objective-C或Swift文件,例如VideoEncoder.swift
,用于配置和执行视频编码。
// VideoEncoder.swift
import Foundation
import AVFoundation
@objc class VideoEncoder: NSObject {
@objc static func encodeVideo(withFilePath inputPath: String, outputPath: String, profileLevelId: String, completion: @escaping (Bool, Error?) -> Void) {
guard let inputURL = URL(fileURLWithPath: inputPath),
let outputURL = URL(fileURLWithPath: outputPath) else {
completion(false, NSError(domain: "", code: -1, userInfo: [NSLocalizedDescriptionKey: "Invalid URL"]))
return
}
let asset = AVAsset(url: inputURL)
guard let track = asset.tracks(withMediaType: .video).first else {
completion(false, NSError(domain: "", code: -1, userInfo: [NSLocalizedDescriptionKey: "No video track found"]))
return
}
let videoComposition = AVMutableVideoComposition()
videoComposition.frameDuration = CMTimeMake(1, 30)
videoComposition.renderSize = track.naturalSize
let instruction = AVMutableVideoCompositionInstruction()
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration)
let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
instruction.layerInstructions = [layerInstruction] as [AVVideoCompositionLayerInstruction]
videoComposition.instructions = [instruction] as [AVVideoCompositionInstruction]
let exporter = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetHighestQuality)
exporter.outputFileType = AVFileType.mp4
exporter.outputURL = outputURL
exporter.videoComposition = videoComposition
// Configure the video settings with profileLevelId
var videoSettings: [AVVideoCompressionPropertiesKey : Any] = [:]
videoSettings[AVVideoCodecKey] = AVVideoCodecType.h264
videoSettings[AVVideoCompressionPropertiesKey.profileLevel] = profileLevelId
videoSettings[AVVideoWidthKey] = track.naturalSize.width
videoSettings[AVVideoHeightKey] = track.naturalSize.height
videoSettings[AVVideoAverageBitRateKey] = 5000000 // Example bitrate
exporter.videoSettings = videoSettings
exporter.exportAsynchronously(completionHandler: {
switch exporter.status {
case .completed:
completion(true, nil)
case .failed:
completion(false, exporter.error)
case .cancelled, .exporting, .waiting, .unknown:
completion(false, NSError(domain: "", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session status not completed"]))
}
})
}
}
Android部分
在android/src/main/java/com/yourpackage/videoencoder
目录下创建一个Java或Kotlin文件,例如VideoEncoder.java
,用于配置和执行视频编码。
// VideoEncoder.java
package com.yourpackage.videoencoder;
import android.media.MediaCodec;
import android.media.MediaFormat;
import android.util.Log;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
public class VideoEncoder {
private static final String TAG = "VideoEncoder";
public static void encodeVideo(String inputPath, String outputPath, String profileLevelId, Callback callback) {
// Note: This is a simplified example. In a real-world scenario, you'd need to set up
// a MediaExtractor to read the input file, a MediaCodec to encode it, and a MediaMuxer to
// write the encoded data to the output file.
// For the sake of this example, we're just logging the parameters.
Log.i(TAG, "Input Path: " + inputPath);
Log.i(TAG, "Output Path: " + outputPath);
Log.i(TAG, "Profile Level ID: " + profileLevelId);
// Here you would set up the MediaCodec with the specified profileLevelId
// and perform the encoding process.
// For demonstration purposes, we'll just call the callback with a success result.
callback.onEncodingComplete(true, null);
}
public interface Callback {
void onEncodingComplete(boolean success, Exception e);
}
}
2. 在Flutter中调用插件
在Flutter项目的lib
目录下创建一个Dart文件,例如video_encoder.dart
,用于封装对原生插件的调用。
import 'dart:async';
import 'dart:typed_data';
import 'package:flutter/services.dart';
class VideoEncoder {
static const MethodChannel _channel = MethodChannel('com.yourpackage/video_encoder');
static Future<void> encodeVideo(String inputPath, String outputPath, String profileLevelId) async {
try {
await _channel.invokeMethod('encodeVideo', {
'inputPath': inputPath,
'outputPath': outputPath,
'profileLevelId': profileLevelId,
});
} on PlatformException catch (e) {
throw FormatException(e.message ?? "Unknown error");
}
}
}
3. 配置原生方法通道
在插件的iOS和Android项目中配置方法通道,以便Flutter可以调用原生方法。
iOS
在ios/Classes/YourPlugin.m
中:
#import <Flutter/Flutter.h>
#import "VideoEncoder.h"
@interface YourPlugin : NSObject<FlutterPlugin>
@end
@implementation YourPlugin
+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
FlutterMethodChannel* channel = [FlutterMethodChannel
methodChannelWithName:@"com.yourpackage/video_encoder"
binaryMessenger:registrar.messenger];
[YourPluginInstance sharedInstance] setupWithChannel:channel];
}
@end
@interface YourPluginInstance : NSObject
+ (instancetype)sharedInstance;
- (void)setupWithChannel:(FlutterMethodChannel*)channel;
@end
@implementation YourPluginInstance
+ (instancetype)sharedInstance {
static YourPluginInstance *instance;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] init];
});
return instance;
}
- (void)setupWithChannel:(FlutterMethodChannel*)channel {
[channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
if ([call.method isEqualToString:@"encodeVideo"]) {
NSDictionary *arguments = call.arguments;
NSString *inputPath = arguments[@"inputPath"];
NSString *outputPath = arguments[@"outputPath"];
NSString *profileLevelId = arguments[@"profileLevelId"];
[VideoEncoder encodeVideoWithFilePath:inputPath
outputPath:outputPath
profileLevelId:profileLevelId
completion:^(BOOL success, NSError *error) {
if (success) {
result(success);
} else {
result(FlutterError(code: @"ERROR", message: error.localizedDescription, details: nil));
}
}];
} else {
result(FlutterMethodNotImplemented);
}
}];
}
@end
Android
在android/src/main/kotlin/com/yourpackage/yourplugin/YourPlugin.kt
中:
package com.yourpackage.yourplugin
import android.content.Context
import androidx.annotation.NonNull
import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.embedding.engine.plugins.activity.ActivityAware
import io.flutter