我有一个加载到内存中的h264video文件，我尝试用imem参数“imem-cat = 4”播放它，这样vlc将使用访问模块来解复用video，而vlc启动并接收我的imem成功参数：

[0x7f38a0000e28] access_imem demux debug: Using get(0x404e1d), release(0x404e91), data(0x7fff5b4a9430), cookie("IMEM") 

这个类别也意味着我不必提供DTS和PTS。 用于VLC的imem模块没有很好的文档logging，但是我已经在几个地方发现了提示，例如

https://forum.videolan.org/viewtopic.php?t=111917

https://forum.videolan.org/viewtopic.php?f=32&t=93842

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在python中使用内存中的libVLC播放video

我的imem-get函数只是简单地将缓冲区指针设置为第一次调用时的video数据，返回0，任何进一步的调用返回1表示没有更多的数据：

 int MyImemGetCallback (void *data, const char *cookie, int64_t *dts, int64_t *pts, unsigned *flags, size_t * bufferSize, void ** buffer) { ImemData* imem = (ImemData*)data; cookie = imem->cookieString; if(imem == NULL || imem->allBuffered==true) //indicate all data has been get()ted return 1; *buffer = (void*) imem->video; bufferSize = (size_t*) &(imem->bytes); imem->allBuffered=true; return 0; } 

不幸的是，在第一次通话后，我收到以下错误：

 [0x189cb18] main input debug: Creating an input for 'imem://' [0x189cb18] main input debug: using timeshift granularity of 50 MiB, in path '/tmp' [0x189cb18] main input debug: `imem://' gives access `imem' demux `' path `' [0x189cb18] main input debug: creating demux: access='imem' demux='' location='' file='(null)' [0x7f2808000e28] main demux debug: looking for access_demux module matching "imem": 20 candidates [0x7f2808000e28] access_imem demux debug: Using get(0x404e1d), release(0x404e91), data(0x7ffe0da3b940), cookie("h264") [0x7f2808000e28] main demux debug: no access_demux modules matched [0x189cb18] main input debug: creating access 'imem' location='', path='(null)' [0x7f2808001958] main access debug: looking for access module matching "imem": 25 candidates [0x7f2808001958] access_imem access debug: Using get(0x404e1d), release(0x404e91), data(0x7ffe0da3b940), cookie("h264") [0x7f2808001958] main access debug: using access module "access_imem" [0x7f2808000e28] main stream debug: Using block method for AStream* [0x7f2808000e28] main stream debug: starting pre-buffering [0x7f2808000e28] main stream error: cannot pre fill buffer [0x7f2808001958] main access debug: removing module "access_imem" [0x189cb18] main input warning: cannot create a stream_t from access [0x17d7298] main libvlc debug: removing all interfaces [0x17d7298] main libvlc debug: exiting [0x17d7298] main libvlc debug: no exit handler [0x17d7298] main libvlc debug: removing stats 

出于某种原因，似乎vlc不能访问video数据，但错误信息并不是很有帮助，通常是指networkingstream而不是内存位置。

有没有人以这种方式成功地使用过imem，或者对这个问题有什么想法？ video完全从磁盘播放VLC。 谢谢你的帮助。

编辑

它看起来像项目接口可能实际上不支持这种方式播放。 但是，libVLC提供了libvlc_media_t和livblc_media_new_callbacks，可以让我实现我想要的。 我会报告回来，如果我得到它的工作。

 LIBVLC_API libvlc_media_t * libvlc_media_new_callbacks (libvlc_instance_t *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) 

 class MemVideoData { public: MemVideoData(char *data, int data_bytes) : video(data), bytes(data_bytes), lastByteIndex(0) {} //init ~MemVideoData() {} char* video; // pointer to video in memory int bytes; int lastByteIndex; }; ssize_t memVideo_read(void *opaque, unsigned char* buf, size_t len) { //TODO: block if not end of stream but no bytes available MemVideoData *mVid = (MemVideoData*) opaque; //cast and give context int bytesToCopy=0; int bytesSoFar = mVid->lastByteIndex; int bytesRemaining = mVid->bytes - mVid->lastByteIndex; if(bytesRemaining >= len) //at least as many bytes remaining as requested { bytesToCopy = len; } else if (bytesRemaining < len) //less that requested number of bytes remaining { bytesToCopy = bytesRemaining; } else { return 0; // no bytes left to copy } char *start = mVid->video; std::memcpy(buf,&start[mVid->lastByteIndex], bytesToCopy); //copy bytes requested to buffer. mVid->lastByteIndex = mVid->lastByteIndex + bytesToCopy; //increment bytes read count return bytesToCopy; } 

 int VideoPlayer::memVideo_open(void* opaque, void** datap, uint64_t* sizep) { MemVideoData *mVid = static_cast<MemVideoData*> (opaque); //cast and give context //TODO: get mutex on MemVideoData object pointed to by opaque *sizep = (uint64_t) mVid->bytesTotal; //set stream length *datap = mVid; /*point to entire object. Think this was intended to point to the raw video data but we use the MemVideoData object in read() and seek()*/ mVid->lastByteReadIndex=0; return 0; }