LVC 播放器buffer自定义读写的方法

LVC 播放器提供buffer自定义读写的方法，但是并没有开放到Java层，并且关于此类的应用也并不多；不过用到的也很少；下面就简单介绍应用的方法：

在LVC 中的lvc\lib\media.c中已经提供其应用接口，接口如下：

libvlc_media_t *libvlc_media_new_callbacks(libvlc_instance_t *p_instance,
                                           libvlc_media_open_cb open_cb,
                                           libvlc_media_read_cb read_cb,
                                           libvlc_media_seek_cb seek_cb,
                                           libvlc_media_close_cb close_cb,
                                           void *opaque)；

简单的使用方法就是在lvclibjni_media.c 实现其jni的接口；方法如下：

static int opaque;static bool isFifoReadStop = false;int media_open_cb(void *opaque, void **datap,uint64_t *sizep){  <pre name="code" class="objc">printf("%s", __FUNCTION__);

return 0;}ssize_t media_read_cb(void *opaque, unsigned char *buf, size_t len){ int readLen = 0; int oneLen = 0; void *p_read_buffer = NULL; readLen = 0;while(isFifoReadStop == false){ oneLen = getFifobuf(&p_read_buffer,len - readLen); if(oneLen > 0) { memcpy(buf+readLen,p_read_buffer,oneLen); readLen += oneLen; } if(readLen >= len) { break; }} if(isFifoReadStop != false) {

printf("media_read_cb  stop read data\n");

return -1; } //printf("read:%ld byte ~ %ld byte\n",readLen,len); if((readLen <= 0) ||(readLen > len)) { printf("media_read_cb no data or stop read len = %d get len = %d\n",readLen,len); readLen = 0; return -1; } return (ssize_t)readLen;}void media_close_cb(void *opaque){

//printf("%s", __FUNCTION__);

}int media_seek_cb(void *opaque, uint64_t offset){ return 0;}voidJava_org_videolan_libvlc_Media_nativeNewFromBufferCallBack(JNIEnv *env, jobject thiz, jobject libVlc){ vlcjni_object *p_obj; int fd = (*env)->GetIntField(env, jfd, fields.FileDescriptor.descriptorID); if ((*env)->ExceptionOccurred(env)) { (*env)->ExceptionClear(env); fd = -1; } if (fd == -1) { throw_IllegalArgumentException(env, "fd invalid"); return; } p_obj = VLCJniObject_newFromJavaLibVlc(env, thiz, libVlc); if (!p_obj) return; p_obj->u.p_m = libvlc_media_new_callbacks(p_obj->p_libvlc, media_open_cb, media_read_cb, media_close_cb, media_seek_cb, &opaque); Media_nativeNewCommon(env, thiz, p_obj);}

在media.java中实现调用

 private native void nativeNewFromBufferCallBack(LibVLC libVLC);    public Media(LibVLC libVLC) {        nativeNewFromBufferCallBack(libVLC);    }

如果，不希望在jni中实现数据的读取接口，则可以在Java中实现，在回调函数中调用Java类中实现的接口即可，此次略过；

实现的另外一种方法，是不通过更改media的jni,而通过更改mediaplay jni来更改media的参数即可；

方法如下：

#include <android/log.h>  #include <vlc/libvlc.h>#include <vlc/libvlc_media.h>#include <vlc/libvlc_media_list.h> // For the subitems, here for convenience#include <vlc/libvlc_events.h>#include <vlc_common.h>#include <vlc_input.h>#include <vlc_meta.h>#include <vlc_playlist.h> /* For the preparser */#include <vlc_url.h>#include "libvlc_internal.h"#include "media_internal.h"#include "Fifobuf.h"....voidJava_org_videolan_libvlc_MediaPlayer_nativeSetMediaBufferCallback(JNIEnv *env,                                                                jobject thiz,                                                                jobject jmedia){     libvlc_media_t *p_m = NULL;    vlcjni_object *p_obj = VLCJniObject_getInstance(env, thiz);    if (!p_obj)        return;    if (jmedia)    {        vlcjni_object *p_m_obj = VLCJniObject_getInstance(env, jmedia);        if (!p_m_obj)            return;        p_m = p_m_obj->u.p_m;        LOGI("register media buffer callback\n");      input_item_AddOpaque(p_m->p_input_item, "imem-data", opaque);      input_item_AddOpaque(p_m->p_input_item, "imem-open", media_open_cb);      input_item_AddOpaque(p_m->p_input_item, "imem-read", media_read_cb);      input_item_AddOpaque(p_m->p_input_item, "imem-seek", media_seek_cb);      input_item_AddOpaque(p_m->p_input_item, "imem-close", media_close_cb);    }}

Java实现如下：

private native void nativeSetMediaBufferCallback(Media media);       public void setSetMediaBufferCallback(Media media)      {           nativeSetMediaBufferCallback(media);       }

调用方法不变，但是参数需要更改为：

      String playUrl = "imem://";  Uri uri = Uri.parse(playUrl);  if(mMedia != null)  {  mMedia.release();  }  mMedia = new Media(libvlc, uri);  mVlcPlayer.setSetMediaBufferCallback(mMedia);  mVlcPlayer.setMedia(mMedia);