<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
That's an interesting file, but I'm not sure it is a a compliant
one: the resolution change is<br>
advertised through SPS in the bitstream, but the MP4 header says
"avc1", which as far as I remembe<br>
means the H264 bitstream should not contain any SPS (please double
check this, haven't looked at the spec).<br>
<br>
Ideally, the tool you produced this file with would use an "avc3"
stream format, and not hold<br>
any parameter sets in its MP4 header. That way, you could detect
resolution changes by simply<br>
plugging a demuxer and a parser together and looking for new caps.
Currently you can only do that<br>
either by also plugging a decoder afterwards and looking for caps
changes, or analysing the SPS<br>
manually :)<br>
<br>
Best,<br>
<br>
<div class="moz-signature">-- <br>
Mathieu Duponchelle · <a href="https://www.centricular.com">https://www.centricular.com</a></div>
<br>
<br>
<div class="moz-cite-prefix">On 12/3/19 10:50 PM, David Ing wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAKF2gC8+z3WyfnX9qX=b-WjGyAG=cQ9w83axLQS3f9YJBnf71g@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">I have an mp4 file which changes size during
playback. But I noticed that gst-discoverer-1.0 does not report
the fact that the size changes.
<div><br>
</div>
<div><span style="background-color:rgb(255,255,0)">I have two
questions</span>.</div>
<div>
<ol>
<li>In theory, what is the fastest way to scan the file to
determine where the size changes?</li>
<li>In practice, what is the easiest way (given the current
state of gstreamer) to scan the file and determine where
the size changes?</li>
</ol>
<div>
<div>Here is the file which changes size during playback:<br>
</div>
</div>
<div><br>
</div>
<blockquote style="margin:0 0 0 40px;border:none;padding:0px">
<div>
<div><a
href="https://drive.google.com/drive/folders/1f4pGNDhzCvsg1xXWj4y9DS3vXkaglOvZ?usp=sharing"
moz-do-not-send="true">https://drive.google.com/drive/folders/1f4pGNDhzCvsg1xXWj4y9DS3vXkaglOvZ?usp=sharing</a></div>
</div>
<div><br>
</div>
</blockquote>
Here is the gst-discoverer-1.0 output:
<div><br>
</div>
<blockquote style="margin:0 0 0 40px;border:none;padding:0px">
<div><font face="monospace">$ <b>gst-discoverer-1.0 -v
screencap.m4v </b></font></div>
<div><font face="monospace">Analyzing
<a class="moz-txt-link-freetext" href="file:///home/ding/mess/repro/screencap.m4v">file:///home/ding/mess/repro/screencap.m4v</a></font></div>
<div><font face="monospace">Done discovering
<a class="moz-txt-link-freetext" href="file:///home/ding/mess/repro/screencap.m4v">file:///home/ding/mess/repro/screencap.m4v</a></font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">Topology:</font></div>
<div><font face="monospace"> container: video/quicktime,
variant=(string)iso</font></div>
<div><font face="monospace"> video: video/x-h264,
stream-format=(string)avc, alignment=(string)au,
level=(string)4.2, profile=(string)main,
codec_data=(buffer)014d402affe1002b674d402a965402a835f35602d40404050000030001000003003ce060007d0000030177009a9503b4244d4001000468ce3520,
width=(int)996, height=(int)632,
pixel-aspect-ratio=(fraction)1/1,
framerate=(fraction)30/1,
interlace-mode=(string)progressive,
chroma-format=(string)4:2:0, bit-depth-luma=(uint)8,
bit-depth-chroma=(uint)8, parsed=(boolean)true</font></div>
<div><font face="monospace"> Tags:</font></div>
<div><font face="monospace"> video codec: H.264 / AVC</font></div>
<div><font face="monospace"> bitrate: 309812</font></div>
<div><font face="monospace"> datetime:
2019-11-01T17:40:33Z</font></div>
<div><font face="monospace"> title: n/a</font></div>
<div><font face="monospace"> container format: ISO
MP4/M4A</font></div>
<div><font face="monospace"> </font></div>
<div><font face="monospace"> Codec:</font></div>
<div><font face="monospace"> video/x-h264,
stream-format=(string)avc, alignment=(string)au,
level=(string)4.2, profile=(string)main,
codec_data=(buffer)014d402affe1002b674d402a965402a835f35602d40404050000030001000003003ce060007d0000030177009a9503b4244d4001000468ce3520,
width=(int)996, height=(int)632,
pixel-aspect-ratio=(fraction)1/1,
framerate=(fraction)30/1,
interlace-mode=(string)progressive,
chroma-format=(string)4:2:0, bit-depth-luma=(uint)8,
bit-depth-chroma=(uint)8, parsed=(boolean)true</font></div>
<div><font face="monospace"> Additional info:</font></div>
<div><font face="monospace"> None</font></div>
<div><font face="monospace"> Stream ID:
14c5bd3783191c8af25f30b00a879f8f7bdaa4367c8ecbd954b38e5367507175/001</font></div>
<div><font face="monospace"> Width: 1350</font></div>
<div><font face="monospace"> Height: 846</font></div>
<div><font face="monospace"> Depth: 24</font></div>
<div><font face="monospace"> Frame rate: 30/1</font></div>
<div><font face="monospace"> Pixel aspect ratio: 1/1</font></div>
<div><font face="monospace"> Interlaced: false</font></div>
<div><font face="monospace"> Bitrate: 309812</font></div>
<div><font face="monospace"> Max bitrate: 0</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">Properties:</font></div>
<div><font face="monospace"> Duration: 0:00:34.861322222</font></div>
<div><font face="monospace"> Seekable: yes</font></div>
<div><font face="monospace"> Live: no</font></div>
<div><font face="monospace"> Tags: </font></div>
<div><font face="monospace"> video codec: H.264 / AVC</font></div>
<div><font face="monospace"> bitrate: 309812</font></div>
<div><font face="monospace"> datetime:
2019-11-01T17:40:33Z</font></div>
<div><font face="monospace"> title: n/a</font></div>
<div><font face="monospace"> container format: ISO
MP4/M4A</font></div>
</blockquote>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
gstreamer-devel mailing list
<a class="moz-txt-link-abbreviated" href="mailto:gstreamer-devel@lists.freedesktop.org">gstreamer-devel@lists.freedesktop.org</a>
<a class="moz-txt-link-freetext" href="https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel">https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a></pre>
</blockquote>
</body>
</html>