mORMot Open Source

Further debugging, ff_h264_init_cabac_states mainly takes time on for loop

Debugging the source code of ffmpeg avcodec_decode_video2, The files involved mainly include h264dec. c, h264_slice. c, and h264_cabac.c。
The main functions are h264_decode_frame ->decodedeal_units ->decode_slice.
The function that takes the longest time is decode_slice. Decode_slice Internal
Brief process: ff_init_cabac_decoder ->ff_h264_init_cabac_states->Ff_h264_decode_mbm_cabac.

In the FPC environment, ff_h264_init_cabac_states and ff_h264_decode_mbm_cabac
The execution efficiency of is only 1/6 of that in the QT environment.

Posting the source code of ff_h264_init_cabac_states will mainly take time on the for loop. Exactly, ff_h264_decode_mb_cabac is also in the
a large amount of for loop, because the h264 frame is composed of many macro blocks, ff_h264_decode_mb_cabac only decodes a single macro block.

void ff_h264_init_cabac_states(const H264Context *h, H264SliceContext *sl)
{
    int ii;
    const int8_t (*tab)[2];
    const int slice_qp = av_clip(sl->qscale - 6*(h->ps.sps->bit_depth_luma-8), 0, 51);

    if (sl->slice_type_nos == AV_PICTURE_TYPE_I)
          tab = cabac_context_init_I;
    else                               
          tab = cabac_context_init_PB[sl->cabac_init_idc];

    //calculate pre-state
    for( ii= 0; ii < 1024; ii++ ) {
        int pre = 2*(((tab[ii][0] * slice_qp) >>4 ) + tab[ii][1]) - 127;

        pre^= pre>>31;
        if(pre > 124)
            pre= 124 + (pre&1);

        sl->cabac_state[ii] =  pre;
    }
}

By using gettickcount for simple timing, avcodec_decode_video2 took 70 milliseconds, mainly due to decoding H264

the ffmpeg and sdl2 dynamic libraries are both loaded in FPC standard mode.
the key is that the avcodec.decode_video2 takes too long.

thank you, ab, I should explain more clearly.
1.   The target task is to use FPC to decode 1080P video files.
2.   The current issue I am facing is that on the aarch64 Linux platform based ubuntu, 
      the decoding efficiency of using FPC to call FFMPEG c library is too low, resulting 70 milliseconds per frame.
      As a comparison, I used QT Creator with the same FFMPEG c library and the same calling method, resulting in 10 milliseconds per second. This is ok.
3.   In my past work experience, I have mostly worked under Windows and Linux, both of which are X86 architectures.
      I used FPC to call FFMPEG c library and completed this task very smoothly.
4.   I placed the code in FTP://1: Test1234@121.40.151.139 /，Please refer to readme.txt
5.   If necessary, please let me know，I can open TeamViewer remotely control.

@PierceNg, thanks. The version of ubuntu22.04 gblic may be higher than 2.27

I am on x86_64 ubuntu 14.04 (GLIBC 2.19) Compilation is normal.

But I need to statically link sqlite3. o on aarch64 Linux.
What should I do to work properly without reporting an error "undefined reference to ` fcntl64 '"