<div dir="ltr">Thank you very much, I'll take some time and look at this tutorial.</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Jul 22, 2014 at 11:22 AM, cyril poulet <span dir="ltr"><<a href="mailto:cyril.poulet@centraliens.net" target="_blank">cyril.poulet@centraliens.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div>I think "<i style="color:rgb(0,0,0);font-family:Roboto,sans-serif;font-size:14px;line-height:19px">For video, the packet contains exactly one frame.</i><font color="#000000" face="Roboto, sans-serif"><span style="font-size:14px;line-height:19px">" is not true for all codecs, but is for most of the usual ones.<br>
</span></font></div><font color="#000000" face="Roboto, sans-serif"><span style="font-size:14px;line-height:19px">try this one : <a href="http://blog.tomaka17.com/2012/03/libavcodeclibavformat-tutorial/" target="_blank">http://blog.tomaka17.com/2012/03/libavcodeclibavformat-tutorial/</a><br>
</span></font></div><font color="#000000" face="Roboto, sans-serif"><span style="font-size:14px;line-height:19px">It may be that avcodec_decode_video2 recognizes that the first packet data is header and discards it as irrelevant for image decoding...<br>
</span></font></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-07-22 17:14 GMT+02:00 Matt Orlando <span dir="ltr"><<a href="mailto:morlando616@gmail.com" target="_blank">morlando616@gmail.com</a>></span>:<div>
<div class="h5"><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">The <a href="https://www.ffmpeg.org/doxygen/trunk/group__lavf__decoding.html#ga4fdb3084415a82e3810de6ee60e46a61" target="_blank">documentation</a> says "<i style="color:rgb(0,0,0);font-family:Roboto,sans-serif;font-size:14px;line-height:19px">For video, the packet contains exactly one frame.</i><font color="#000000" face="Roboto, sans-serif"><span style="font-size:14px;line-height:19px">" I used </span></font><a href="http://dranger.com/ffmpeg/" style="color:rgb(0,0,0);font-family:Roboto,sans-serif;font-size:14px;line-height:19px" target="_blank">this</a><font color="#000000" face="Roboto, sans-serif"><span style="font-size:14px;line-height:19px"> tutorial to understand the flow of what needs to be done. Some of the calls were deprecated so a few google searches got me the replacements. What appears to be happening is those lost frames are just gone...the data isn't being accumulated. Is it possible my av_free_packet call is in a bad spot?</span></font></div>
<div><div>
<div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Jul 22, 2014 at 10:58 AM, cyril poulet <span dir="ltr"><<a href="mailto:cyril.poulet@centraliens.net" target="_blank">cyril.poulet@centraliens.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div>what av_read_frame does is take some data and fill your packet with it. There is no guaranty that a full frame is in the packet, or even image data.<br>
</div>avcodec_decode_video2 is the only way to know if you have decoded an image : you feed it your successive packets, it accumulates data, and tells you when the data allowed him to successfully decode an image (through frameFinished)<br>
</div>You should look online for basic examples of how to decode safely vids, there is in particular a tutorial which introduces the structure SafePacket (first version has been updated for latest versions of the libs)<br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-07-22 16:49 GMT+02:00 Matt Orlando <span dir="ltr"><<a href="mailto:morlando616@gmail.com" target="_blank">morlando616@gmail.com</a>></span>:<div>
<div><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Thanks for the response. That's very interesting, though I wonder if it could actually be header related. Based on the videos, I know for sure there are exactly 64 frames in the first movie, for instance. My m_FrameRead is only increased if avcodec_decode_video2 says it was able to get a picture. My thinking is that if it was a header that was read, that function wouldn't set frameFinished to "true". So av_read_frame hits the EOF when my m_FrameRead counter is only 56.<div>
<br></div><div>Are you saying that perhaps the av_read_frame is reading a bunch of data (header + frames) and my avcodec_decode_video2 says there's no picture because there's header data in there. Then a few frames later (or maybe next frame), av_read_frame reads more data, now including the 9th 'frame' and finally avcodec_decode_video2 decodes and I increment my counter (which would be now 1 when I'd want it to be 9).<br>
<div><br></div><div>Thanks for the help!</div><span><font color="#888888"><div>-Matt</div></font></span></div></div><div><div><div class="gmail_extra"><br><br><div class="gmail_quote">
On Tue, Jul 22, 2014 at 8:30 AM, cyril poulet <span dir="ltr"><<a href="mailto:cyril.poulet@centraliens.net" target="_blank">cyril.poulet@centraliens.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div>according to the doc, av_read_packet does not check wether the data in the decoded frame is a valid image or not.<br>
</div>As it is always the 8 first "frames" missing, I would assume it is the header that gets decoded first.<br>
</div>Have you noticed missing images when comparing the first real decoded image and your stream in a player ?<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-07-21 18:37 GMT+02:00 Matt Orlando <span dir="ltr"><<a href="mailto:morlando616@gmail.com" target="_blank">morlando616@gmail.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div><div dir="ltr">Hi folks,<div><br></div><div>I'm having some trouble with the decoding of my h.264 movies. I've tested with different videos, one 64 frames long and another 52 frames long. In both cases, the first 8 frames (exactly 8) weren't decoding. In other words, the call to avcodec_decode_video2 returns 0 for the got_picture variable. I track the frames read and received for our system and I never get notice that all the frames were read because my counter doesn't increase for the first 8...however all of the subsequent calls to av_read_frame return EOF. To prevent any confusion (or perhaps just to add some context), I need the raw data from each decoded frame since I don't treat them as a frame to a movie but rather a frame of x,y,z positional data.</div>
<div><br></div><div>I work in Unity but made a plugin to communicate with the libraries to read and decode the h.264 movies. This is our update function:</div><div><br></div><div><span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">bool H264Stream::Update(int desiredFrame)</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">{</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> if( desiredFrame <= m_FrameRead )</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> return true;</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"><span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> int frameFinished = 0;</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"><span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> if( av_read_frame( m_AVFormat, &m_Packet ) >= 0 )</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> {</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> if( m_Packet.stream_index == m_AVStream->index )</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> {</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> av_frame_unref( m_AVFrame );</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> avcodec_decode_video2( m_AVContext, m_AVFrame, &frameFinished, &m_Packet );</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"><span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> if( frameFinished != 0 )</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> {</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> sws_scale( m_SwsContext, m_AVFrame->data, m_AVFrame->linesize, 0, m_AVContext->height, m_Picture->data, m_Picture->linesize );</span></div>
<div><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"><span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> m_FrameRead++;</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"><span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> av_free_packet( &m_Packet );</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> }</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> }</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> }</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"><span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px"> return m_FrameRead >= desiredFrame;</span><br style="margin:0px;padding:0px;color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">
<span style="color:rgb(46,139,87);font-family:Monaco,'Andale Mono','Courier New',Courier,mono;font-size:12px;line-height:15.210000038146973px">}</span><br></div><div><br></div><div><br></div><div>Oh, quick note, this is my first time using these libraries so if there's something blatantly wrong with how I'm doing this, please let me know. :) Just keep in mind, it's the full frame of 'raw' data I use (post-decode) that I pass back into my Unity c# scripts.</div>
<div><br></div><div>Thanks for the help everyone!</div><span><font color="#888888"><div>-Matt</div></font></span></div>
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