gstreamer decoder
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Hi all!
The gstreamer framework uses ffmpeg codecs to encode/decode data? The problem is that: I have a mini video surveillance system that runs on linux, and I developed a decoder plugin based on ffmpeg and Intel IPP. The configuration file tells what is the decoder plugin to use (ffmpeg or IPP shared libraries) to decode compressed images. What I need to now is that: the decoders that gstreamer uses are the same that ffmpeg implements? Or can I develop a gstreamer plugin for my application that uses decoders from gstreamer? thanks, Nuno Cardoso. ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/gstreamer-devel |
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Hi,
On Fri, Mar 19, 2010 at 8:08 AM, Nuno Cardoso <[hidden email]> wrote: > Hi all! > > The gstreamer framework uses ffmpeg codecs to encode/decode data? The > problem is that: I have a mini video surveillance system that runs on linux, > and I developed a decoder plugin based on ffmpeg and Intel IPP. The > configuration file tells what is the decoder plugin to use (ffmpeg or IPP > shared libraries) to decode compressed images. What I need to now is that: > the decoders that gstreamer uses are the same that ffmpeg implements? Or can > I develop a gstreamer plugin for my application that uses decoders from > gstreamer? gst-ffmpeg supports most codecs that your system's ffmpeg installation supports. Gstreamer also has its own suite of plugins not dependent on ffmpeg that reside in the packages gst-plugins-*, gst-opengl, and so forth. To answer your first question: only if you want it to be that way. If your pipeline contains ffmux_*, ffdemux_* or similar elements, those will call directly into ffmpeg for the low-level codec operations. To answer your second question: I'm assuming by "gstreamer plugin for my application" that you mean your app has a multiple multimedia backend architecture. If that's the case, then you can almost certainly make your app a gstreamer client (link against gstreamer or import the python modules) as one alternative, and as part of that functionality, you can use gstreamer elements that rely on ffmpeg, such as ffdemux_*. If I understand you correctly, you have developed a custom codec within the ffmpeg library, and you want to expose that to gstreamer clients. To do that, you will probably have to hack on the gstreamer-ffmpeg sources to enable that. I've never hacked on gst-ffmpeg, and this HACKING guide may be completely outdated, but the current advice ( http://cgit.freedesktop.org/gstreamer/gst-ffmpeg/tree/HACKING ) suggests that you will need to make some relatively simple additions to expose your codec. That's assuming, of course, that your codec is a "proper' ffmpeg codec that implements the right interfaces in the public ffmpeg API. If not, you'll have a harder time binding it. HTH, Sean > > thanks, > Nuno Cardoso. > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _______________________________________________ > gstreamer-devel mailing list > [hidden email] > https://lists.sourceforge.net/lists/listinfo/gstreamer-devel > > ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/gstreamer-devel |
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In reply to this post by Nuno Cardoso-2
Most of codecs don't use ffmpeg's codecs. There is a separate plugin, gst-ffmpeg, which uses ffmpeg's muxers, demuxers and codecs. Surely, nothing can stop you from developing a plugin. There is a Plugin Writers' Guide and a template, which you can get from git repository. However, FFmpeg is very different from the GStreamer in the concepts. FFmpeg allows you to get an encoded frame or a decoded picture in memory (and encoding also). If you need to draw it, or sync with audio data, then you're on your own. GStreamer provides a pipeline, allowing media data to stream from a source (file, device, network server, ...) to a sink (screen, sound card, file, etc) and takes care about synchronization. |
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My application had a pipeline execution model based on plugin filters, like GStreamer and DirectShow:
aquisition => decompression => processing => vizualization => compression => storage => transmission The main codecs that the decompression uses are: jpeg, mpeg4 and h264 (the codecs used by camera manufacturers). If I run my application in a Intel based machine, I'm using Intel IPP to do the decoding, but if I'm using a AMD or some kind of embeded systems that uses ffmpeg, I use ffmpeg to decode frames. Suppose that I want to use OMAP from Texas Instruments.... that board uses GStreamer with a plugin from texas that use the texas DSP. Is it possible I call a Gstreamer API to do only the decoding step? like I do with ffmpeg.... bool load_decoder(...) { /* alloc and initialize AVCodecContext */ m_pCodecCtx = avcodec_alloc_context(); /* set AVCodecContext properties */ m_pCodecCtx->codec_type = CODEC_TYPE_VIDEO; /* video codec type */ if (_cameraInfo.decoder == "mpeg4") { m_pCodecCtx->codec_id = CODEC_ID_MPEG4; /* MJPEG decoder id */ } else if (_cameraInfo.decoder == "jpeg") { m_pCodecCtx->codec_id = CODEC_ID_MJPEG; /* MJPEG decoder id */ } else if (_cameraInfo.decoder == "h264") { m_pCodecCtx->codec_id = CODEC_ID_H264; /* MJPEG decoder id */ } m_pCodecCtx->width = _cameraInfo.width; /* image width */ m_pCodecCtx->height = _cameraInfo.height; /* image height */ m_pCodecCtx->flags |= CODEC_FLAG_EMU_EDGE | CODEC_FLAG_PART; /* find the decoder for the video stream */ m_pCodec = avcodec_find_decoder(m_pCodecCtx->codec_id); if (!m_pCodec) { m_strError = string("Unable to locate codec decoder"); return false; } /* open codec */ if (avcodec_open(m_pCodecCtx, m_pCodec) < 0) { m_strError = "Cannot open codec"; return false; } /* alloc audio/video frame */ m_pFrame = avcodec_alloc_frame(); if (!m_pFrame) { m_strError = "Cannot alloc audio/video frame"; return false; } } 2010/3/19 wl2776 <[hidden email]>
------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/gstreamer-devel |
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I'm afraid that's a hard hackish work. To do it, you have to simulate the environment, which a bin gives to an element. This will require digging deeply in GStreamer's binary interface in order to get pointers to the functions and call them with the prepared structures. http://www.gstreamer.net/data/doc/gstreamer/head/gstreamer/html/GstPlugin.html Plugin DLLs on windows export only gst_plugin_desc, which is a structure. |
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Sorry, forgot a very important thing. There are an appsrc and an appsink elements, which allow you to feed a pipeline with your application generated data and get pipeline's data into your application. So, you can set up a small bin: appsrc -> decoder -> appsink and get the output of the appsink (decoded samples) into your application. |
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