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• ffv1 : Drop unnecessary casts and const qualifiers to match function signatures

  18 décembre 2014, par Diego Biurrun

  ffv1 : Drop unnecessary casts and const qualifiers to match function signatures
  libavcodec/ffv1dec.c:898:36 : warning : cast discards ‘const’ qualifier from pointer target type
  

  • [DBH] libavcodec/ffv1dec.c

• Faster way to append to PyList in c++

  19 décembre 2022, par Timothy Halim

  I'm new to c++ and looking for a faster way to append pixel value to python list, since currrently on loop it takes around 0.1 second to process one frame of image with resolution of 854x480, do anyone have any idea ?

  


  I tried to avoid using third party module if possible.

  


  Here is what I've got so far :

  


  PyObject* byte_list = PyList_New(static_cast(0));

AVFrame *pFrameRGB = av_frame_alloc();
av_frame_copy_props(pFrameRGB, this->pFrame);
pFrameRGB->width = this->pFrame->width;
pFrameRGB->height = this->pFrame->height;
pFrameRGB->format = AV_PIX_FMT_RGB24;
av_frame_get_buffer(pFrameRGB, 0);

sws_scale(this->swsCtx, this->pFrame->data, this->pFrame->linesize, 0, 
        this->pCodecContext->height, pFrameRGB->data, pFrameRGB->linesize);

if (this->_debug) {
    std::cout << "Frame linesize " << pFrameRGB->linesize[0] << "\n";
    std::cout << "Frame width " << pFrameRGB->width << "\n";
    std::cout << "Frame height " << pFrameRGB->height << "\n";
}

// This looping method seems slow
for(int y = 0; y < pFrameRGB->height; ++y) {
    for(int x = 0; x < pFrameRGB->width; ++x) {
        int p = x * 3 + y * pFrameRGB->linesize[0];
        int r = pFrameRGB->data[0][p];
        int g = pFrameRGB->data[0][p+1];
        int b = pFrameRGB->data[0][p+2];
        PyList_Append(byte_list, PyLong_FromLong(r));
        PyList_Append(byte_list, PyLong_FromLong(g));
        PyList_Append(byte_list, PyLong_FromLong(b));
    }
}

av_frame_free(&pFrameRGB);


  


  Thanks !

  


• Some videos fail to chromecast with error MEDIA_UNKNOWN

  1er juin 2020, par JonasVautherin

  Using mkchromecast to cast local mp4 files, some videos work, and some don't (as in : the screen hangs on the blue chromecast logo, suggesting that the initial connection worked). I can reproduce exactly the issue described here.

  



  So I decided to go one level lower, with pychromecast, and try to see what actually happens when it hangs on the blue logo. I converted two videos to HLS format, and exposed them through an http server. The video that works with mkchromecast also works with my setup, but the one that fails, well... fails on both. With pychromecast, I don't get much more information than :

  



  


  ERROR, code 100 : MEDIA_UNKNOWN.

  


  



  From the Cast documentation, this error means :

  



  


  The media element encountered an unknown error fired from platform. The media element encountered an error that did not indicate it's one of MediaError.MEDIA_ERR_*. This should be rare.

  


  



  It is not rare for me at all, though. I thought that maybe the failing video was in an unsupported format, as described in the documentation. So I tried to compare both videos with the following command :

  



  ffprobe -v quiet -print_format json -show_streams 


  



  Video that works :

  



  {
    "streams": [
        {
            "index": 0,
            "codec_name": "h264",
            "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
            "profile": "High",
            "codec_type": "video",
            "codec_time_base": "1001/48000",
            "codec_tag_string": "avc1",
            "codec_tag": "0x31637661",
            "width": 1920,
            "height": 1080,
            "coded_width": 1920,
            "coded_height": 1088,
            "has_b_frames": 2,
            "sample_aspect_ratio": "1:1",
            "display_aspect_ratio": "16:9",
            "pix_fmt": "yuv420p",
            "level": 50,
            "chroma_location": "left",
            "refs": 1,
            "is_avc": "true",
            "nal_length_size": "4",
            "r_frame_rate": "24000/1001",
            "avg_frame_rate": "24000/1001",
            "time_base": "1/24000",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 47127080,
            "duration": "1963.628333",
            "bit_rate": "5527977",
            "bits_per_raw_sample": "8",
            "nb_frames": "47080",
            "disposition": {
                "default": 1,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0
            },
            "tags": {
                "language": "und",
                "handler_name": "VideoHandler"
            }
        },
        {
            "index": 1,
            "codec_name": "aac",
            "codec_long_name": "AAC (Advanced Audio Coding)",
            "profile": "LC",
            "codec_type": "audio",
            "codec_time_base": "1/48000",
            "codec_tag_string": "mp4a",
            "codec_tag": "0x6134706d",
            "sample_fmt": "fltp",
            "sample_rate": "48000",
            "channels": 2,
            "channel_layout": "stereo",
            "bits_per_sample": 0,
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/48000",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 94254528,
            "duration": "1963.636000",
            "bit_rate": "125776",
            "max_bit_rate": "125776",
            "nb_frames": "92048",
            "disposition": {
                "default": 1,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0
            },
            "tags": {
                "language": "und",
                "handler_name": "SoundHandler"
            }
        }
    ]
}


  



  Video that does NOT work :

  



  {                                               
    "streams": [
        {
            "index": 0,
            "codec_name": "h264",
            "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
            "profile": "High",
            "codec_type": "video",
            "codec_time_base": "125/5994",
            "codec_tag_string": "avc1",
            "codec_tag": "0x31637661",
            "width": 1920,
            "height": 1040,
            "coded_width": 1920,
            "coded_height": 1040,
            "has_b_frames": 2,
            "sample_aspect_ratio": "1:1",
            "display_aspect_ratio": "24:13",
            "pix_fmt": "yuv420p",
            "level": 41,
            "chroma_location": "left",
            "refs": 1,
            "is_avc": "true",
            "nal_length_size": "4",
            "r_frame_rate": "2997/125",
            "avg_frame_rate": "2997/125",
            "time_base": "1/11988",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 97032000,
            "duration": "8094.094094",
            "bit_rate": "2499644",
            "bits_per_raw_sample": "8",
            "nb_frames": "194064",
            "disposition": {
                "default": 1,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0
            },
            "tags": {
                "creation_time": "2020-03-27T09:56:39.000000Z",
                "language": "und",
                "handler_name": "L-SMASH Video Media Handler"
            }
        },
        {
            "index": 1,
            "codec_name": "aac",
            "codec_long_name": "AAC (Advanced Audio Coding)",
            "profile": "LC",
            "codec_type": "audio",
            "codec_time_base": "1/48000",
            "codec_tag_string": "mp4a",
            "codec_tag": "0x6134706d",
            "sample_fmt": "fltp",
            "sample_rate": "48000",
            "channels": 6,
            "channel_layout": "5.1",
            "bits_per_sample": 0,
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/48000",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 388516320,
            "duration": "8094.090000",
            "bit_rate": "224000",
            "max_bit_rate": "224000",
            "nb_frames": "379413",
            "disposition": {
                "default": 1,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0
            },
            "tags": {
                "creation_time": "2020-03-27T09:56:39.000000Z",
                "language": "eng",
                "handler_name": "SoundHandler"
            }
        }
    ]
}


  



  For what I can see, the codecs are the same, and the only difference I can make is in the aspect ratio.

  



  What could be the reason for this "MEDIA_UNKNOWN" error on the chromecast side ? Is there something more I could compare between those two videos ? Could it be that the chromecast fails because of the aspect ratio ?