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• regarding h264_qsv encoding speed in ffmpeg

  31 janvier 2021, par TONY

  As we know, now ffmpeg supports intel hardware encoding(h264 qsv).
But it doesn't support "ultra fast", is there any settings to improve the encoding speed ?

  


  m_encoder = avcodec_find_encoder_by_name("h264_qsv");
if(m_encoder == nullptr){
    LOG(ERROR)<<"Find H264 Encoder failed";
    return false;
}
m_ctx = avcodec_alloc_context3(m_encoder);
m_ctx->bit_rate = bitrate_kbps*1024;
m_ctx->width = m_width;
m_ctx->height = m_height;
m_ctx->time_base = { 1, (int)fps };
m_ctx->qmin = 10;
m_ctx->qmax = 35;
m_ctx->gop_size = fps;
m_ctx->max_b_frames = 0;
m_ctx->has_b_frames = false;

m_ctx->codec_id = m_encoder->id;
m_ctx->codec_type = AVMEDIA_TYPE_VIDEO;
m_ctx->pix_fmt = m_h264InputFormat;

AVDictionary *param = nullptr;
av_dict_set(&param, "look_ahead", "0", 0);
av_dict_set(&param, "look_ahead_depth", "8", 0);
av_dict_set(&param, "preset", "veryfast", 0);
av_dict_set(&param, "tune", "zerolatency", 0);

int ret = avcodec_open2(m_ctx, m_encoder, &param);


  


• Most generic ffmpeg command to truncate video [duplicate]

  18 octobre 2014, par David542

  This question already has an answer here :

  • ffmpeg command to extract first two minutes of a video
    
    1 answer
    

  I have several thousand videos that I would like to truncate the video to the first two minutes. Here is the command I’m using so far :

  ffmpeg -i %s -ss 0 -t 120 %s' % (input_path, output_path)

  However, this runs into many errors on valid files. Is there an ’ultra-generic’ command I can use to truncate the file to the first two minutes, and it will work with all videos ?

• h264 Licensing, ffmpeg iPhone transcoding

  28 février 2013, par NadavRub

  Requirements
  
  1. An application that should run, to begin with, on iPhone, and, in the end on a plurality
   of SmartPhone devices.
  2. Aim at having the trans-coding code supporting as much OSs as possible.
  3. Application is commercial.

  Use-case
  
  I. Record video using the portable SmartPhone Camera application
  II. Trans-code the video into a plurality of bit-rates using a cutom app
  

  iPhone Implementation
  
  A. To satisfy requirement [2], Implement Trans-coding using C++
  B. Use ffmpeg for trans-coding.
  

  Problem
  - Using ffmpeg to encode H264 req usage of the x264 lib
  - H264 encoding mandate payment for Licensing.

  In order to avoid H264 Licensing
  - The iPhone device ( and many others ) come with built-in H264 encoding capability
  - Usage of the built-in H264 Codec will avoid licensing problems/restrictions
  

  ---

  Does ffmpeg, supports, in any way, usage of iPhone's built-in H264 encoder ?
  
  
  
  Any help will be appreciated.