1# Media Data Multiplexing 2 3You can call the native APIs provided by the AVMuxer module to multiplex audio and video streams, that is, to store encoded audio and video data to a file in a certain format. 4 5For details about the supported multiplexing formats, see [AVCodec Supported Formats](avcodec-support-formats.md#media-data-multiplexing). 6 7<!--RP2--><!--RP2End--> 8 9**Usage Scenario** 10 11- Video and audio recording 12 13 After you encode audio and video streams, multiplex them into files. 14 15- Audio and video editing 16 17 After you edit audio and video, multiplex them into files. 18 19- Audio and video transcoding 20 21 After you transcode audio and video, multiplex them into files. 22 23## How to Develop 24 25Read [AVMuxer](../../reference/apis-avcodec-kit/_a_v_muxer.md) for the API reference. 26 27> **NOTE** 28> 29> To call the AVMuxer module to write a local file, request the **ohos.permission.READ_MEDIA** and **ohos.permission.WRITE_MEDIA** permissions by following the instructions provided in [Requesting User Authorization](../../security/AccessToken/request-user-authorization.md). 30 31### Linking the Dynamic Library in the CMake Script 32 33``` cmake 34target_link_libraries(sample PUBLIC libnative_media_avmuxer.so) 35target_link_libraries(sample PUBLIC libnative_media_core.so) 36``` 37 38### How to Develop 39 40The following walks you through how to implement the entire process of audio and video multiplexing. It uses the MP4 format as an example. 41 42For details about the keys to be configured for different container formats, see [AVCodec Supported Formats](avcodec-support-formats.md#media-data-multiplexing). 43 441. Add the header files. 45 46 ```c++ 47 #include <multimedia/player_framework/native_avmuxer.h> 48 #include <multimedia/player_framework/native_avcodec_base.h> 49 #include <multimedia/player_framework/native_avformat.h> 50 #include <multimedia/player_framework/native_avbuffer.h> 51 #include <fcntl.h> 52 ``` 53 542. Call **OH_AVMuxer_Create()** to create an **OH_AVMuxer** instance. 55 56 ```c++ 57 // Set the container format to MP4. 58 OH_AVOutputFormat format = AV_OUTPUT_FORMAT_MPEG_4; 59 // Create an FD in read/write mode. 60 int32_t fd = open("test.mp4", O_CREAT | O_RDWR | O_TRUNC, S_IRUSR | S_IWUSR); 61 OH_AVMuxer *muxer = OH_AVMuxer_Create(fd, format); 62 ``` 63 643. (Optional) Call **OH_AVMuxer_SetRotation()** to set the rotation angle. 65 66 ```c++ 67 // Set the rotation angle when a video image needs to be rotated. 68 OH_AVMuxer_SetRotation(muxer, 0); 69 ``` 70 714. Add file-level data. 72 ```c++ 73 OH_AVFormat *format = OH_AVFormat_Create(); // Use OH_AVFormat_Create to create a format. 74 OH_AVFormat_SetStringValue(format, OH_MD_KEY_CREATION_TIME, "2024-12-28T00:00:00:000000Z"); // Set the creation time (UTC time in ISO 8601 format). 75 int ret = OH_AVMuxer_SetFormat(muxer, format); // Set format data to the muxer. 76 if (ret != AV_ERR_OK) { 77 // Failed to set the format because no valid key data to be written is found. 78 } 79 OH_AVFormat_Destroy(format); // Destroy the format. 80 ``` 81 825. Add an audio track. 83 84 **Method 1: Use OH_AVFormat_Create to create the format.** 85 86 ```c++ 87 int audioTrackId = -1; 88 uint8_t *buffer = ...; // Encoding configuration data. If there is no configuration data, leave the parameter unspecified. 89 size_t size = ...; // Length of the encoding configuration data. Set this parameter based on project requirements. 90 OH_AVFormat *formatAudio = OH_AVFormat_Create(); // Call OH_AVFormat_Create to create a format. The following showcases how to multiplex an AAC-LC audio with the sampling rate of 44100 Hz and two audio channels. 91 OH_AVFormat_SetStringValue(formatAudio, OH_MD_KEY_CODEC_MIME, OH_AVCODEC_MIMETYPE_AUDIO_AAC); // Mandatory. 92 OH_AVFormat_SetIntValue(formatAudio, OH_MD_KEY_AUD_SAMPLE_RATE, 44100); // Mandatory. 93 OH_AVFormat_SetIntValue(formatAudio, OH_MD_KEY_AUD_CHANNEL_COUNT, 2); // Mandatory. 94 OH_AVFormat_SetIntValue(formatAudio, OH_MD_KEY_PROFILE, AAC_PROFILE_LC); // Optional. 95 OH_AVFormat_SetBuffer(formatAudio, OH_MD_KEY_CODEC_CONFIG, buffer, size); // Optional. 96 97 int ret = OH_AVMuxer_AddTrack(muxer, &audioTrackId, formatAudio); 98 if (ret != AV_ERR_OK || audioTrackId < 0) { 99 // Failure to add the audio track. 100 } 101 OH_AVFormat_Destroy (formatAudio); // Destroy the format. 102 ``` 103 104 **Method 2: Use OH_AVFormat_CreateAudioFormat to create the format.** 105 106 ```c++ 107 int audioTrackId = -1; 108 uint8_t *buffer = ...; // Encoding configuration data. If there is no configuration data, leave the parameter unspecified. 109 size_t size = ...; // Length of the encoding configuration data. Set this parameter based on project requirements. 110 OH_AVFormat *formatAudio = OH_AVFormat_CreateAudioFormat(OH_AVCODEC_MIMETYPE_AUDIO_AAC, 44100, 2); 111 OH_AVFormat_SetIntValue(formatAudio, OH_MD_KEY_PROFILE, AAC_PROFILE_LC); // Optional. 112 OH_AVFormat_SetBuffer(formatAudio, OH_MD_KEY_CODEC_CONFIG, buffer, size); // Optional. 113 114 int ret = OH_AVMuxer_AddTrack(muxer, &audioTrackId, formatAudio); 115 if (ret != AV_ERR_OK || audioTrackId < 0) { 116 // Failure to add the audio track. 117 } 118 OH_AVFormat_Destroy (formatAudio); // Destroy the format. 119 ``` 120 1216. Add a video track. 122 123 **Method 1: Use OH_AVFormat_Create to create the format.** 124 125 ```c++ 126 int videoTrackId = -1; 127 uint8_t *buffer = ...; // Encoding configuration data. If there is no configuration data, leave the parameter unspecified. 128 size_t size = ...; // Length of the encoding configuration data. Set this parameter based on project requirements. 129 OH_AVFormat *formatVideo = OH_AVFormat_Create(); 130 OH_AVFormat_SetStringValue(formatVideo, OH_MD_KEY_CODEC_MIME, OH_AVCODEC_MIMETYPE_VIDEO_AVC); // Mandatory. 131 OH_AVFormat_SetIntValue(formatVideo, OH_MD_KEY_WIDTH, 1280); // Mandatory. 132 OH_AVFormat_SetIntValue(formatVideo, OH_MD_KEY_HEIGHT, 720); // Mandatory. 133 OH_AVFormat_SetBuffer(formatVideo, OH_MD_KEY_CODEC_CONFIG, buffer, size); // Optional. 134 135 int ret = OH_AVMuxer_AddTrack(muxer, &videoTrackId, formatVideo); 136 if (ret != AV_ERR_OK || videoTrackId < 0) { 137 // Failure to add the video track. 138 } 139 OH_AVFormat_Destroy(formatVideo); // Destroy the format. 140 ``` 141 142 **Method 2: Use OH_AVFormat_CreateVideoFormat to create the format.** 143 144 ```c++ 145 int videoTrackId = -1; 146 uint8_t *buffer = ...; // Encoding configuration data. If there is no configuration data, leave the parameter unspecified. 147 size_t size = ...; // Length of the encoding configuration data. Set this parameter based on project requirements. 148 OH_AVFormat *formatVideo = OH_AVFormat_CreateVideoFormat(OH_AVCODEC_MIMETYPE_VIDEO_AVC, 1280, 720); 149 OH_AVFormat_SetBuffer(formatVideo, OH_MD_KEY_CODEC_CONFIG, buffer, size); // Optional. 150 151 int ret = OH_AVMuxer_AddTrack(muxer, &videoTrackId, formatVideo); 152 if (ret != AV_ERR_OK || videoTrackId < 0) { 153 // Failure to add the video track. 154 } 155 OH_AVFormat_Destroy(formatVideo); // Destroy the format. 156 ``` 157 1587. Add a cover track. 159 160 **Method 1: Use OH_AVFormat_Create to create the format.** 161 162 ```c++ 163 int coverTrackId = -1; 164 OH_AVFormat *formatCover = OH_AVFormat_Create(); 165 OH_AVFormat_SetStringValue(formatCover, OH_MD_KEY_CODEC_MIME, OH_AVCODEC_MIMETYPE_IMAGE_JPG); 166 OH_AVFormat_SetIntValue(formatCover, OH_MD_KEY_WIDTH, 1280); 167 OH_AVFormat_SetIntValue(formatCover, OH_MD_KEY_HEIGHT, 720); 168 169 int ret = OH_AVMuxer_AddTrack(muxer, &coverTrackId, formatCover); 170 if (ret != AV_ERR_OK || coverTrackId < 0) { 171 // Failure to add the cover track. 172 } 173 OH_AVFormat_Destroy(formatCover); // Destroy the format. 174 ``` 175 176 **Method 2: Use OH_AVFormat_CreateVideoFormat to create the format.** 177 178 ```c++ 179 int coverTrackId = -1; 180 OH_AVFormat *formatCover = OH_AVFormat_CreateVideoFormat(OH_AVCODEC_MIMETYPE_IMAGE_JPG, 1280, 720); 181 182 int ret = OH_AVMuxer_AddTrack(muxer, &coverTrackId, formatCover); 183 if (ret != AV_ERR_OK || coverTrackId < 0) { 184 // Failure to add the cover track. 185 } 186 OH_AVFormat_Destroy(formatCover); // Destroy the format. 187 ``` 188 1898. Call **OH_AVMuxer_Start()** to start multiplexing. 190 191 ```c++ 192 // Call Start() to write the file header. After this API is called, you cannot set media parameters or add tracks. 193 if (OH_AVMuxer_Start(muxer) != AV_ERR_OK) { 194 // Handle exceptions. 195 } 196 ``` 197 1989. Call **OH_AVMuxer_WriteSampleBuffer()** to write data. 199 200 The encapsulated data includes video, audio, and cover data. 201 202 ```c++ 203 // Data can be written only after Start() is called. 204 int size = ...; 205 OH_AVBuffer *sample = OH_AVBuffer_Create(size); // Create an AVBuffer instance. 206 // Write data to the sample buffer by using OH_AVBuffer_GetAddr(sample). For details, see the usage of OH_AVBuffer. 207 // Multiplex the cover. One image must be written at a time. 208 209 // Set buffer information. 210 OH_AVCodecBufferAttr info = {0}; 211 info.pts =...; // Playback start time of the current data, in microseconds. The relative time is used. 212 info.size = size; // Length of the current data. 213 info.offset = 0; // Offset. Generally, the value is 0. 214 info.flags |= AVCODEC_BUFFER_FLAGS_SYNC_FRAME; // Flag of the current data. For details, see OH_AVCodecBufferFlags. 215 info.flags |= AVCODEC_BUFFER_FLAGS_CODEC_DATA; // The AVC in annex-b format contains the codec configuration flag. 216 OH_AVBuffer_SetBufferAttr(sample, &info); // Set the buffer attribute. 217 int trackId = audioTrackId; // Select the audio or video track to be written. 218 219 int ret = OH_AVMuxer_WriteSampleBuffer(muxer, trackId, sample); 220 if (ret != AV_ERR_OK) { 221 // Handle exceptions. 222 } 223 ``` 224 22510. Call **OH_AVMuxer_Stop()** to stop multiplexing. 226 227 ```c++ 228 // Call Stop() to write the file trailer. After this API is called, you cannot write media data. 229 if (OH_AVMuxer_Stop(muxer) != AV_ERR_OK) { 230 // Handle exceptions. 231 } 232 ``` 233 23411. Call **OH_AVMuxer_Destroy()** to release the instance. 235 236 Do not repeatedly destroy the instance. Otherwise, the program may crash. 237 238 ```c++ 239 if (OH_AVMuxer_Destroy(muxer) != AV_ERR_OK) { 240 // Handle exceptions. 241 } 242 muxer = NULL; 243 close(fd); // Close the FD. 244 ```