Audio and Video Encapsulation

You can call the native APIs provided by the AVMuxer module to encapsulate audio and video, that is, to store encoded audio and video data to a file in a certain format.

Currently, the following encapsulation capabilities are supported:

Usage Scenario

• Video and audio recording

After you encode audio and video streams, encapsulate them into files.

• Audio and video editing

After you edit audio and video, encapsulate them into files.

• Audio and video transcoding

After you transcode audio and video, encapsulate them into files.

How to Develop

Read AVMuxer for the API reference.

NOTE

To call the encapsulation APIs to write a local file, request the ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA permissions by following the instructions provided in Applying for Permissions.

Linking the Dynamic Library in the CMake Script

target_link_libraries(sample PUBLIC libnative_media_avmuxer.so)

How to Develop

The following walks you through how to implement the entire process of audio and video encapsulation. It uses the MP4 format as an example.

1. Call OH_AVMuxer_Create() to create an OH_AVMuxer instance.

   // Set the encapsulation format to MP4.
   OH_AVOutputFormat format = AV_OUTPUT_FORMAT_MPEG_4;
   // Create a File Descriptor (FD) in read/write mode.
   int32_t fd = open("test.mp4", O_CREAT|O_RDWR|O_TRUNC, S_IRUSR|S_IWUSR);
   OH_AVMuxer *muxer = OH_AVMuxer_Create(fd, format);

1. (Optional) Call OH_AVMuxer_SetRotation() to set the rotation angle.

   // Set the rotation angle when a video image needs to be rotated.
   OH_AVMuxer_SetRotation(muxer, 0);

1. Add an audio track.

Method 1: Use OH_AVFormat_Create to create the format.

   int audioTrackId = -1;
   OH_AVFormat *formatAudio = OH_AVFormat_Create();
   OH_AVFormat_SetStringValue(formatAudio, OH_MD_KEY_CODEC_MIME, OH_AVCODEC_MIMETYPE_AUDIO_AAC); // Mandatory.
   OH_AVFormat_SetIntValue(formatAudio, OH_MD_KEY_AUD_SAMPLE_RATE, 44100); // Mandatory.
   OH_AVFormat_SetIntValue(formatAudio, OH_MD_KEY_AUD_CHANNEL_COUNT, 2); // Mandatory.
   
   int ret = OH_AVMuxer_AddTrack(muxer, &audioTrackId, formatAudio);
   if (ret != AV_ERR_OK||audioTrackId < 0) {
       // Failure to add the audio track.
   }
   OH_AVFormat_Destroy (formatAudio); // Destroy the format.

Method 2: Use OH_AVFormat_CreateAudioFormat to create the format.

   int audioTrackId = -1;
   OH_AVFormat *formatAudio = OH_AVFormat_CreateAudioFormat(OH_AVCODEC_MIMETYPE_AUDIO_AAC, 44100, 2);
   
   int ret = OH_AVMuxer_AddTrack(muxer, &audioTrackId, formatAudio);
   if (ret != AV_ERR_OK||audioTrackId < 0) {
       // Failure to add the audio track.
   }
   OH_AVFormat_Destroy (formatAudio); // Destroy the format.

1. Add a video track.

Method 1: Use OH_AVFormat_Create to create the format.

   int videoTrackId = -1;
   uint8_t *buffer = ...; // Encoding configuration data. If there is no configuration data, leave the parameter unspecified.
   size_t size =...; // Length of the encoding configuration data. Set this parameter based on project requirements.
   OH_AVFormat *formatVideo = OH_AVFormat_Create();
   OH_AVFormat_SetStringValue(formatVideo, OH_MD_KEY_CODEC_MIME, OH_AVCODEC_MIMETYPE_VIDEO_MPEG4); // Mandatory.
   OH_AVFormat_SetIntValue(formatVideo, OH_MD_KEY_WIDTH, 1280); // Mandatory.
   OH_AVFormat_SetIntValue(formatVideo, OH_MD_KEY_HEIGHT, 720); // Mandatory.
   OH_AVFormat_SetBuffer(formatVideo, OH_MD_KEY_CODEC_CONFIG, buffer, size); // Optional
   
   int ret = OH_AVMuxer_AddTrack(muxer, &videoTrackId, formatVideo);
   if (ret != AV_ERR_OK||videoTrackId < 0) {
       // Failure to add the video track.
   }
   OH_AVFormat_Destroy(formatVideo); // Destroy the format.

Method 2: Use OH_AVFormat_CreateVideoFormat to create the format.

   int videoTrackId = -1;
   uint8_t *buffer = ...; // Encoding configuration data. If there is no configuration data, leave the parameter unspecified.
   size_t size =...; // Length of the encoding configuration data. Set this parameter based on project requirements.
   OH_AVFormat *formatVideo = OH_AVFormat_CreateVideoFormat(OH_AVCODEC_MIMETYPE_VIDEO_MPEG4, 1280, 720);
   OH_AVFormat_SetBuffer(formatVideo, OH_MD_KEY_CODEC_CONFIG, buffer, size); // Optional
   
   int ret = OH_AVMuxer_AddTrack(muxer, &videoTrackId, formatVideo);
   if (ret != AV_ERR_OK||videoTrackId < 0) {
       // Failure to add the video track.
   }
   OH_AVFormat_Destroy(formatVideo); // Destroy the format.

1. Add a cover track.

Method 1: Use OH_AVFormat_Create to create the format.

   int coverTrackId = -1;
   OH_AVFormat *formatCover = OH_AVFormat_Create();
   OH_AVFormat_SetStringValue(formatCover, OH_MD_KEY_CODEC_MIME, OH_AVCODEC_MIMETYPE_IMAGE_JPG);
   OH_AVFormat_SetIntValue(formatCover, OH_MD_KEY_WIDTH, 1280);
   OH_AVFormat_SetIntValue(formatCover, OH_MD_KEY_HEIGHT, 720);
   
   int ret = OH_AVMuxer_AddTrack(muxer, &coverTrackId, formatCover);
   if (ret != AV_ERR_OK||coverTrackId < 0) {
       // Failure to add the cover track.
   }
   OH_AVFormat_Destroy(formatCover); // Destroy the format.

Method 2: Use OH_AVFormat_CreateVideoFormat to create the format.

   int coverTrackId = -1;
   OH_AVFormat *formatCover = OH_AVFormat_CreateVideoFormat(OH_AVCODEC_MIMETYPE_IMAGE_JPG, 1280, 720);
   
   int ret = OH_AVMuxer_AddTrack(muxer, &coverTrackId, formatCover);
   if (ret != AV_ERR_OK||coverTrackId < 0) {
       // Failure to add the cover track.
   }
   OH_AVFormat_Destroy(formatCover); // Destroy the format.

1. Call OH_AVMuxer_Start() to start encapsulation.

   // Call Start() to write the file header. After this API is called, you cannot set media parameters or add tracks.
   if (OH_AVMuxer_Start(muxer) != AV_ERR_OK) {
       // Exception handling.
   }

1. Call OH_AVMuxer_WriteSample() to write data, including video, audio, and cover data.

   // Data can be written only after Start() is called.
   int size = ...;
   OH_AVMemory *sample = OH_AVMemory_Create (size); // Create an AVMemory instance.
   // Write data to the sample buffer. For details, see the usage of OH_AVMemory.
   // Encapsulate the cover. One image must be written at a time.
   
   // Set buffer information.
   OH_AVCodecBufferAttr info;
   info.pts =...; // Playback start time of the current data, in microseconds.
   info.size = size; // Length of the current data.
   info.offset = 0; // Offset. Generally, the value is 0.
   info.flags|= AVCODEC_BUFFER_FLAGS_SYNC_FRAME; // Flag of the current data. For details, see OH_AVCodecBufferFlags.
   int trackId = audioTrackId; // Select the track to be written.
   
   int ret = OH_AVMuxer_WriteSample(muxer, trackId, sample, info);
   if (ret != AV_ERR_OK) {
       // Exception handling.
   }

1. Call OH_AVMuxer_Stop() to stop encapsulation.

   // Call Stop() to write the file trailer. After this API is called, you cannot write media data.
   if (OH_AVMuxer_Stop(muxer) != AV_ERR_OK) {
       // Exception handling.
   }

1. Call OH_AVMuxer_Destroy() to release the instance.

   if (OH_AVMuxer_Destroy(muxer) != AV_ERR_OK) {
       // Exception handling.
   }
   muxer = NULL;
   close(fd); // Close the FD.

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