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FFmpegVideoProvider is used to store, obtain, and control stream data. It only supports storing data of the AVPacket type; The data in AVPacket can be YUV, H264, or MJPG. All of its APIs are thread-safe.

API Instructions

namespace com { namespace sunplus { namespace media {

class FFmpegVideoProvider {
public:
    FFmpegVideoProvider(AVStream* avStream, int maxQueueSize = 4);
    ~FFmpegVideoProvider();

public:	
    void prepare();
    void destroy();

    AVStream* getAVStream();

    void setPutFrameInterval(int interval);

	int putFrame(AVPacket* packet);
    int getFrame(AVPacket*& packet);
};

}}}

Constructors

FFmpegVideoProvider(AVStream* avStream, int maxQueueSize = 4);

prepare

Initialize the internal queue. You can only putFrame/getFrame after preparing.

/**
 * Initialize the internal queue. 
 * You can only putFrame/getFrame after preparing.
 */
void prepare();

destroy

Empty the cached data and release the related resources. After destroying, the putFrame/getFrame returns a failure.

/**
 * Empty the cached data and release the related resources.
 * After destroy, the putFrame/getFrame returns a failure.
 */
void destroy();

getAVStream

Get AVStream to get the stream info of the cached data. Please refer to the getAVStream of FFmpegV4L2VideoSource.

/**
 * Get the AVStream for AVFormatContext, It can be used to get stream information. 
 * Such as time_base, start_time, codec, etc.
 */
AVStream* getAVStream();

setPutFrameInterval

Set the put frame interval, which can be used to implement frame rate control. It is invalid for H264 data.

/* set the put frame interval. It is invalid for H264 data.
 * This way, you can change the frame rate of the stream. 
 * For example, if the frame rate of the Video Source is 30 
 * and you set the interval of the put frame to 3, 
 * the frame rate of this provider will become 10.
 * */ 
void setPutFrameInterval(int interval);

putFrame

Create a new packet that references the same data as the src packet, then push the new packet into the queue. The src packet must be freed with av_packet_unref()+av_packet_free() when it is no longer needed.

/**
 * Cache frame into the queue.
 * the packet must be freed with av_packet_unref()+av_packet_free() when
 * it is no longer needed. 
 * @return 0 if OK, < 0 on error. 
 */
int putFrame(AVPacket* packet);

Sample

AVPacket* packet;

auto ret = av_read_frame(fmtCtx, packet);

if (ret < 0) {
    return ret;
}

ret = provider->putFrame(packet);

/* it is no longer needed, free it */
/* as below, is only unreferenced the buffer referenced by the packet */ 
av_packet_unref(packet);

/* as below, free the packet, the packet will be set to NULL.*/ 
av_packet_free(&packet);

getFrame

Get cached frame from the queue, which is a thread-safe API. After successfully obtaining the packet, it must be freed with av_packet_unref()+av_packet_free() when it is no longer needed.

/**
 * Get cached frame from the queue.
 * On success, the packet must be freed with av_packet_unref()+av_packet_free() when
 * it is no longer needed. 
 * @return 0 if OK, < 0 on error. 
 */
int getFrame(AVPacket*& packet);

Sample

AVPacket* packet;
auto ret = provider->getFrame(packet);

/* copy frame or write frame to file */ 
......

/* it is no longer needed, free it */
/* as below, is only unreferenced the buffer referenced by the packet */ 
av_packet_unref(packet);

/* as below, free the packet, the packet will be set to NULL.*/ 
av_packet_free(&packet);

Sample Code

Please refer to the sample code of FFmpegV4L2VideoSource.

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