<div>Very grateful to that.</div><div><div><br></div><div><br></div><div style="font-size: 12px;font-family: Arial Narrow;padding:2px 0 2px 0;">------------------ 原始邮件 ------------------</div><div style="font-size: 12px;background:#efefef;padding:8px;"><div><b>发件人:</b> "Strahinja Radman"<dr.strashni@gmail.com>;</div><div><b>发送时间:</b> 2019年12月2日(星期一) 下午5:03</div><div><b>收件人:</b> "This list is about using libavcodec, libavformat, libavutil,libavdevice and libavfilter."<libav-user@ffmpeg.org>;<wbr></div><div></div><div><b>主题:</b> Re: [Libav-user] videorate realtime-adjusting</div></div><div><br></div><div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Dec 2, 2019 at 9:29 AM 田浩杨 <<a href="mailto:734512183@qq.com">734512183@qq.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div>I have a question. How can I modify the video-encode bitrate in real time during coding after the video encoder has been turned on? Here's what I did (take x264-encoder as an example) :</div><div><br></div><div>step1.</div><div>Modified the definition of structural AVCoder to add a function pointer.</div><div><span style="white-space:pre-wrap"> </span>int (*valid_context)(AVCodecContext*);</div><div><br></div><div>step2.</div><div>Added function definition to enable the codec rate of x264.</div><div>static int X264_config(AVCodecContext* avctx){</div><div> X264Context* x4 = avctx->priv_data;</div><div> if(avctx->bit_rate){</div><div> x4->params.rc.i_bitrate = avctx->bit_rate / 1000;</div><div> }</div><div> avctx->bit_rate = x4->params.rc.i_bitrate*1000;</div><div> return 0;</div><div>}</div><div><br></div><div>step3.</div><div>build AVCodec.</div><div>AVCodec ff_libx264_encoder = {</div><div> .name = "libx264",</div><div> .long_name = NULL_IF_CONFIG_SMALL("libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"),</div><div> .type = AVMEDIA_TYPE_VIDEO,</div><div> .id = AV_CODEC_ID_H264,</div><div> .priv_data_size = sizeof(X264Context),</div><div> .init = X264_init,</div><div> //</div><div> .valid_context = X264_config,</div><div> //</div><div> .encode2 = X264_frame,</div><div> .close = X264_close,</div><div> .capabilities = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_AUTO_THREADS,</div><div> .priv_class = &x264_class,</div><div> .defaults = x264_defaults,</div><div> .init_static_data = X264_init_static,</div><div> .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE |</div><div> FF_CODEC_CAP_INIT_CLEANUP,</div><div> .wrapper_name = "libx264",</div><div>};</div><div><br></div><div>step4.</div><div>FFmpeg interface layer.</div><div>int attribute_align_arg avcodec_valid_codec_Context(AVCodecContext* avctx){</div><div> int ret = 0;</div><div> ret = avctx->codec->valid_context(avctx);</div><div> if(ret){</div><div> av_log(avctx, AV_LOG_ERROR, "valid context error, ERROR CODE:%d\n", </div><div><span style="white-space:pre-wrap"> </span>ret);</div><div> }</div><div> return ret;</div><div>}</div><div><br></div><div>step5.</div><div>Whenever the application layer needs to modify the bit rate, then App should modify the AVCodecContext-> bit_rate, and then call the above interface to make the Context take effect in the encoder.</div><div><br></div><div>Because of the limited understanding of ffmpeg. So if there is a better way, also hope to give instruction.</div></div>_______________________________________________<br>
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<a href="mailto:libav-user-request@ffmpeg.org" target="_blank">libav-user-request@ffmpeg.org</a> with subject "unsubscribe".</blockquote></div><br clear="all"><div><br></div><div>Well, according to the libx264.c wrapper and x264's encoder.c code, one can simply change the value</div><div>of bitrate, bufsize, maxrate or crf in AVCodecContext, and reconfig_encoder will invoke x264's internal</div><div>API that will reconfigure the encoder with one or more of the previously mentioned values. That should</div><div>be it. The change will be triggered on the next sent frame. Checkout the source of libx264.c line 186.</div><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><br>Regards<br>Strahinja Radman</div></div></div>