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<p class="MsoNormal">Hello, <o:p></o:p></p>
<p class="MsoNormal">Due to memory usage, we need to use a buffered solution to load a small chunk of blocks of streams in memory instead of loading the whole stream with:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> avformat_network_init();<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> std::</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:#2B91AF">uint8_t</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
*avioc_buffer =<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">static_cast</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"><</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:#2B91AF">uint8_t</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
*> (av_malloc(AV_BUFFER_BLOCK_SIZE));<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> avioc_ = avio_alloc_context(<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> avioc_buffer, AV_BUFFER_BLOCK_SIZE, 0, &data_provider_,
<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> &ReadAVBlockCallback,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">nullptr</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">nullptr</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> fmtc_ = avformat_alloc_context();<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> fmtc_->pb = avioc_[</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:gray">idx</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">];<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> fmtc_->flags |=
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:#6F008A">AVFMT_FLAG_CUSTOM_IO</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> avformat_open_input(&fmtc_,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">nullptr</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">nullptr</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">nullptr</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">);</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">ReadAVBlockCallback
</span>is the callback provided to refill the new block.<o:p></o:p></p>
<p class="MsoNormal">AV_BUFFER_BLOCK_SIZE is 8Mytes.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The issue is that I need to implement the seek feature with <span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
av_seek_frame </span>API and<span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> av_seek_frame
</span>is not calling the callback<span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">, “</span>ReadAVBlockCallback” to fill the buffer when needed if the frame to seek is not in the current buffer block.<o:p></o:p></p>
<p class="MsoNormal">I am using FFmpeg 4.1 (and the same issue in 4.4).<o:p></o:p></p>
<p class="MsoNormal">I’ve rebuilt FFmpeg to look at it with the debugger.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What I have observed is that: <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">“av_index_search_timestamp”
</span>call is looking at<span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> “stream’s index_entries”
</span>and if the entry for the seek point is found, and returned, it does not need to call the callback to refill the<span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> “stream buffer”.<o:p></o:p></span></p>
<p class="MsoNormal">But the problem is that this buffer does not have the packet with this seek timestamp, therefore, it cannot seek to the correct keyframe.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here is the code snap from matroskadec.c<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">if</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> ((index = av_index_search_timestamp(st,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:gray">timestamp</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:gray">flags</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">)) < 0 || index == st->nb_index_entries - 1) {
</span><b><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:red">//if the index is valid, no need to refill the stream buffer but the current buffer does not always have the target frame.<o:p></o:p></span></b></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> avio_seek(</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:gray">s</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">->pb,
st->index_entries[st->nb_index_entries - 1].pos,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:#6F008A">SEEK_SET</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> matroska->current_id = 0;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">while</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> ((index = av_index_search_timestamp(st,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:gray">timestamp</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">,
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:gray">flags</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">)) < 0 || index == st->nb_index_entries - 1) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> matroska_clear_queue(matroska);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">if</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> (matroska_parse_cluster(matroska) < 0)
</span><b><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:red">// this is where the new block is load</span></b><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">
</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:blue">break</span><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black">;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.5pt;font-family:"Cascadia Mono";color:black"> }</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Can you please let me know how I can fix it? Is there a solution in the new releases?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you, a lot. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:12.0pt;font-family:"Arial",sans-serif;color:#94B200"><img width="141" height="48" style="width:1.4687in;height:.5in" id="Picture_x0020_1" src="cid:image001.jpg@01D9E002.97FCE4F0"><span style="mso-ligatures:none"><o:p></o:p></span></span></b></p>
<p class="MsoNormal"><span style="mso-ligatures:none;mso-fareast-language:EN-GB">Baris Unal<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none;mso-fareast-language:EN-GB">Software Engineer III<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none;mso-fareast-language:EN-GB"><a href="mailto:baris.unal@statsperform.global">baris.unal@statsperform.global</a>
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none;mso-fareast-language:EN-GB"><a href="http://www.statsperform.com">www.statsperform.com</a><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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