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    25 avril 2011, par

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Sur d’autres sites (10856)

  • Trying to fix VPlayer's seeking ability, need some guidance [Android FFmpeg]

    1er juin 2016, par vxh.viet

    I’m trying to fix the currently broken seeking ability of VPlayer which is a FFmpeg player for Android. Being a Java developer, C code looks like alien language to me so can only fix it using common logic (which could make any C veteran have a good laugh).

    The relevant file is player.c and I’ll try my best to point out the relevant modification.

    So the basic idea is because FFmpeg’s av_seek_frame is very inaccurate even with AVSEEK_FLAG_ANY so I’m trying to follow this suggestion to seek backward to the nearest keyframe and then decode to the frame I want. One addition note is since I want to seek based on millisecond while the said solution show the way to seek by frame which is potentially a source of problem.

    In the Player I add the following fields :

    struct Player{
    ....
    AVFrame *frame;
    int64_t current_time_stamp;
    };

    In the player_read_from_stream I modify the seeking part as :

    void * player_read_from_stream(void *data) {
       ...
       struct DecoderData *decoder_data = data;
       int stream_no = decoder_data->stream_no;
       AVCodecContext * ctx = player->input_codec_ctxs[stream_no];
       ...
       // seeking, start my stuff
       if(av_seek_frame(player->input_format_ctx, seek_input_stream_number, seek_target, AVSEEK_FLAG_BACKWARD) >= 0){
           //seek to key frame success, now need to read every frame from the key frame to our target time stamp


           while(player->current_time_stamp < seek_target){

               int frame_done;

               while (av_read_frame(player->input_format_ctx, &packet) >= 0) {
                   if (packet.stream_index == seek_input_stream_number) {

                       avcodec_decode_video2(ctx, player->frame, &frame_done, &packet);
                       LOGI(1,"testing_stuff ctx %d", *ctx);
                       if (frame_done) {

                           player->current_time_stamp = packet.dts;
                           LOGI(1,"testing_stuff current_time_stamp: %"PRId64, player->current_time_stamp);
                           av_free_packet(&packet);
                           return;
                       }
                   }
                   av_free_packet(&packet);
               }
           }


       }
       //end my stuff

       LOGI(3, "player_read_from_stream seeking success");

       int64_t current_time = av_gettime();
       player->start_time = current_time - player->seek_position;
       player->pause_time = current_time;        
    }

    And in player_alloc_frames I allocate the memory for my frame as :

    int player_alloc_frames(struct Player *player) {
       int capture_streams_no = player->caputre_streams_no;
       int stream_no;
       for (stream_no = 0; stream_no < capture_streams_no; ++stream_no) {
           player->input_frames[stream_no] = av_frame_alloc();

           //todo: test my stuff
           player->frame = av_frame_alloc();
           //end test

           if (player->input_frames[stream_no] == NULL) {
               return -ERROR_COULD_NOT_ALLOC_FRAME;
           }
       }
       return 0;
    }

    Currently it just keep crashing and being a typical Android NDK’s "feature", it just provide a super helpful stack trace :

    libc: Fatal signal 11 (SIGSEGV), code 1, fault addr 0x40 in tid 2717 (FFmpegReadFromS)

    I very much appreciate if anyone could help me solve this problem. Thank you for your time.

  • Revision 3d181a4516 : Adjust speed setting for temporal layers in 1 pass non-rd mode. For speed 7, re

    11 août 2015, par Marco

    Changed Paths :
     Modify /vp9/encoder/vp9_speed_features.c



    Adjust speed setting for temporal layers in 1 pass non-rd mode.

    For speed 7, real-time mode : Base layer frames are further apart
    (for #temporal layers = 3, this is every 4 frames) so worth keeping
    same motion search parameters (as in speed 6) on the base layer frames.

    Change-Id : Idebf49dda6ef4f3d9a55aee55129a68253f692fb

  • Revision a46f5459c3 : improved speed of 4x4 sse2 fdct. * speed improvment of 30 percent achieved * mu

    3 mars 2014, par Andrew Russell

    Changed Paths :
     Modify /vp9/encoder/x86/vp9_dct_sse2.c



    improved speed of 4x4 sse2 fdct.

    * speed improvment of 30 percent achieved
    * multiplies and adds remain the same
    * non-arithmetic instructions minimized by hand, by :
    -expanding 2 pass loop
    -removing irrelivant "shuffles"
    -combining last two rounding steps
    * further improvments may be possible

    Change-Id : Idec2c3f52910c48e6a0e0f9aefed5cae31b0b8c0