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• How to raw TS packets off a file/url — Without decoding

  15 août 2019, par Znura

  New to ffmpeg and playing around that to understand better. I’m trying to use ffmpeg code base to get TS packets from a HLS Streaming server. I don’t need any decoding as I just have to store the TS packets to be processed later.

  First I built a minimal FFMPEG as outlined in https://zeranoe.com/forum/viewtopic.php?f=5&t=7426. No decoders and only hls and mpegts demuxers. Then using the following code to receive the frames. While inspecting it doesn’t seem to be MPEG-TS packets while looking into buffers thru GDB. Attaching the code here..

  Two Questions :

  1. Shouldn’t the av_recv_frame get me the TS packets ? However When I trace all the way to playlists (off HLSContext), the read_buffer there contains TS packets. IS there any example I could look into to get TS packets in this scenario without decoders ?

  2. If I get answer for (1), How to get the best stream off the HLS server ? when looking into ffplay, av_find_best_stream() sounds like the one to look into.. But again without needing to decode, is there a way to get best one according to the network condition ?

  Thanks..

  I dumped whatever I got off av_recv_frame() and stored in file. This file is not playable with VLC but Windows Movies & TV player could play the sound with missing frames..

  int main(int argc, char *argv[]) { 
  
      AVFormatContext * ifmt_ctx = NULL; 
  
      char *in_filename = NULL; 
  
      int ret = 0; 
  
      AVPacket pkt; 
  
      if (argc != 2) { return 1; } 
  
      in_filename = argv[1]; 
  
      av_register_all();
  
  
  
      if (!(ifmt_ctx = avformat_alloc_context())) { goto end; } 
  
      if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) { 
  
          fprintf(stderr, "Could not open input file '%s'", in_filename); 
  
          goto end; 
  
      } 
  
      if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) { 
  
          fprintf(stderr, "Failed to retrieve input stream information"); 
  
          goto end; 
  
      }
  
  
  
      av_dump_format(ifmt_ctx, 0, in_filename, 0); 
  
      while (1) { 
  
          ret = av_read_frame(ifmt_ctx, &pkt); 
  
          if (ret < 0) break; 
  
          av_free_packet(&pkt); 
  
      } 
  
      end: avformat_close_input(&ifmt_ctx); return 0; 
  
  } 

• lavc/opusdsp : rewrite R-V V postfilter

  2 novembre 2023, par Rémi Denis-Courmont

  lavc/opusdsp : rewrite R-V V postfilter
  This uses a more traditional approach allowing up processing of up to
  
  period minus two elements per iteration. This also allows the algorithm
  
  to work for all and any vector length.
  As the T-Head C908 device under test can load 16 elements loop, there is
  
  unsurprisingly a little performance drop when the period is minimal and
  
  the parallelism is capped at 13 elements :
  Before :
  
  postfilter_15_c :         21222.2
  
  postfilter_15_rvv_f32 :   22007.7
  
  postfilter_512_c :        20189.7
  
  postfilter_512_rvv_f32 :  22004.2
  
  postfilter_1022_c :       20189.7
  
  postfilter_1022_rvv_f32 : 22004.2
  After :
  
  postfilter_15_c :         20189.5
  
  postfilter_15_rvv_f32 :    7057.2
  
  postfilter_512_c :        20189.5
  
  postfilter_512_rvv_f32 :   5667.2
  
  postfilter_1022_c :       20192.7
  
  postfilter_1022_rvv_f32 :  5667.2
  

  • [DH] libavcodec/riscv/opusdsp_init.c
  • [DH] libavcodec/riscv/opusdsp_rvv.S

• lavu/riscv : CPU flag for the Zbb extension

  2 octobre 2022, par Rémi Denis-Courmont

  lavu/riscv : CPU flag for the Zbb extension
  Unfortunately, it is common, and will remain so, that the Bit
  
  manipulations are not enabled at compilation time. This is an official
  
  policy for Debian ports in general (though they do not support RISC-V
  
  officially as of yet) to stick to the minimal target baseline, which
  
  does not include the B extension or even its Zbb subset.
  For inline helpers (CPOP, REV8), compiler builtins (CTZ, CLZ) or
  
  even plain C code (MIN, MAX, MINU, MAXU), run-time detection seems
  
  impractical. But at least it can work for the byte-swap DSP functions.
  

  • [DH] libavutil/cpu.c
  • [DH] libavutil/cpu.h
  • [DH] libavutil/riscv/cpu.c
  • [DH] tests/checkasm/checkasm.c