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• Extract frames as images from an RTMP stream in real-time

  7 novembre 2014, par SoftForge

  I am streaming short videos (4 or 5 seconds) encoded in H264 at 15 fps in VGA quality from different clients to a server using RTMP which produced an FLV file. I need to analyse the frames from the video as images as soon as possible so I need the frames to be written as PNG images as they are received.

  Currently I use Wowza to receive the streams and I have tried using the transcoder API to access the individual frames and write them to PNGs. This partially works but there is about a second delay before the transcoder starts processing and when the stream ends Wowza flushes its buffers causing the last second not to get transcoded meaning I can lose the last 25% of the video frames. I have tried to find a workaround but Wowza say that it is not possible to prevent the buffer getting flushed. It is also not the ideal solution because there is a 1 second delay before I start getting frames and I have to re-encode the video when using the transcoder which is computationally expensive and unnecessarily for my needs.

  I have also tried piping a video in real-time to FFmpeg and getting it to produce the PNG images but unfortunately it waits until it receives the entire video before producing the PNG frames.

  How can I extract all of the frames from the stream as close to real-time as possible ? I don’t mind what language or technology is used as long as it can run on a Linux server. I would be happy to use FFmpeg if I can find a way to get it to write the images while it is still receiving the video or even Wowza if I can find a way not to lose frames and not to re-encode.

  Thanks for any help or suggestions.

• AVC-Intra support

  20 juillet 2013, par Kieran Kunhya

  AVC-Intra support
  This format has been reverse engineered and x264’s output has almost exactly
  
  the same bitstream as Panasonic cameras and encoders produce. It therefore does
  
  not comply with SMPTE RP2027 since Panasonic themselves do not comply with
  
  their own specification. It has been tested in Avid, Premiere, Edius and
  
  Quantel.
  Parts of this patch were written by Jason Garrett-Glaser and some reverse
  
  engineering was done by Joseph Artsimovich.
  

  • [DH] common/common.c
  • [DH] common/common.h
  • [DH] common/set.h
  • [DH] encoder/analyse.c
  • [DH] encoder/encoder.c
  • [DH] encoder/ratecontrol.c
  • [DH] encoder/set.c
  • [DH] encoder/set.h
  • [DH] x264.c
  • [DH] x264.h

• Quick Sync Video-Transcoding by FFMPEG API

  8 octobre 2020, par Paul_ghost

  I want to use Quick Sync Video technology for transcoding h264 to mjpeg. So I tried it with ffmpeg API in C. And I got some problems with that. So, for understanding hardware transcoding I explored "qsvdec.c" and "vaapi_transcode.c" from https://github.com/FFmpeg/FFmpeg/tree/master/doc/examples. But when I tried to add encoding to "qsvdec.c" (p.s. in function "decode_packet" where comment say put your code) :

  


   encoder_ctx->hw_frames_ctx = av_buffer_ref(decoder_ctx->hw_frames_ctx);
            if (!encoder_ctx->hw_frames_ctx) {
                ret = AVERROR(ENOMEM);
                goto fail;
            }
            encoder_ctx->time_base = input_ctx->time_base;
            encoder_ctx->pix_fmt   = AV_PIX_FMT_QSV;
            encoder_ctx->width     = decoder_ctx->width;
            encoder_ctx->height    = decoder_ctx->height;

            if ((ret = avcodec_open2(encoder_ctx, enc_codec, NULL)) < 0) { //enc_codec is mjpeg
                fprintf(stderr, "Failed to open encode codec. Error code: %s\n",
                        av_err2str(ret));
                goto fail;
            }



  


  I got error "Failed to open encoder codec error code function not implemented". So what is the reason for this ? Where i can find a tutorial for hardware in ffmpeg API ?