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Apr 7, 2025
Merged

more generic filter example that also encodes the result #151

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1 change: 1 addition & 0 deletions example/api2-samples/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ set(TARGETS
api2-decode-audio
api2-decode-rasample-audio
api2-decode-encode-audio
api2-decode-filter-encode
api2-dict-basic
api2-timestamp
api2-demux-seek
Expand Down
145 changes: 112 additions & 33 deletions example/api2-samples/api2-decode-filter.cpp → ...pi2-samples/api2-decode-filter-encode.cpp
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Expand Up @@ -24,6 +24,9 @@
using namespace std;
using namespace av;

// Example that uses a complex filter to produce a good
// animated GIF from a video

int main(int argc, char **argv)
{
if (argc < 2)
Expand All @@ -33,6 +36,7 @@ int main(int argc, char **argv)
av::setFFmpegLoggingLevel(AV_LOG_DEBUG);

string uri{argv[1]};
string out{argv[2]};

ssize_t videoStream = -1;
VideoDecoderContext vdec;
Expand Down Expand Up @@ -98,6 +102,45 @@ int main(int argc, char **argv)
}
}

//
// OUTPUT
//
OutputFormat ofrmt;
FormatContext octx;

ofrmt.setFormat(string(), out);
octx.setFormat(ofrmt);

Codec ocodec = findEncodingCodec(ofrmt);
cout << "Codec: " << ocodec.name() << endl;
VideoEncoderContext encoder {ocodec};

// Settings
encoder.setWidth(320);
encoder.setHeight(200);
encoder.setPixelFormat(AV_PIX_FMT_PAL8);
encoder.setTimeBase(Rational {1, 1000});
encoder.setBitRate(vdec.bitRate());

encoder.open(Codec(), ec);
if (ec) {
cerr << "Can't opent encodec\n";
return 1;
}

Stream ost = octx.addStream(encoder);
ost.setFrameRate(vst.frameRate());

octx.openOutput(out, ec);
if (ec) {
cerr << "Can't open output\n";
return 1;
}

octx.dump();
octx.writeHeader();
octx.flush();

// Setup filter
Filter filter_buffer_src{"buffer"};
Filter filter_buffer_sink{"buffersink"};
Expand All @@ -122,9 +165,16 @@ int main(int argc, char **argv)
}

// Setup the filter chain
filter_graph.parse("scale=320x200", src_ctx, sink_ctx, ec);
if (ec)
{
string filterChain;
if (argc > 3) {
filterChain = argv[3];
} else {
filterChain = "scale=320x200:-1:flags=lanczos,split [s0][s1]; "
"[s0] palettegen [p]; [s1][p] paletteuse[f]; ";
}
cout << "Filter: " << filterChain << endl;
filter_graph.parse(filterChain, src_ctx, sink_ctx, ec);
if (ec) {
clog << "Error parsing filter chain: " << ec << ", " << ec.message() << endl;
return 1;
}
Expand Down Expand Up @@ -169,7 +219,13 @@ int main(int argc, char **argv)
continue;
}

frame.setTimeBase(encoder.timeBase());
frame.setStreamIndex(0);
frame.setPictureType();

// Push into the filter
cout << "Pushing frame into filter: " << frame.width() << "x" << frame.height() << ", size=" << frame.size()
<< ", ts=" << frame.pts() << ", tb: " << frame.timeBase() << endl;
buffer_src.addVideoFrame(frame, AV_BUFFERSRC_FLAG_KEEP_REF, ec);
if (ec)
{
Expand All @@ -181,55 +237,78 @@ int main(int argc, char **argv)
VideoFrame filtered;
while (buffer_sink.getVideoFrame(filtered, ec))
{
filtered.setTimeBase(frame.timeBase());
filtered.setTimeBase(encoder.timeBase());
auto ts = filtered.pts();

clog << " filtered: " << filtered.width() << "x" << filtered.height() << ", size=" << filtered.size()
<< ", ts=" << ts << ", tm: " << ts.seconds() << ", tb: " << filtered.timeBase()
<< ", ref=" << filtered.isReferenced() << ":" << filtered.refCount() << endl;

// Encode
Packet opkt = filtered ? encoder.encode(filtered, ec) : encoder.encode(ec);
if (ec) {
cerr << "Encoding error: " << ec << endl;
return 1;
}

if (opkt) {
// Only one output stream
opkt.setStreamIndex(0);

clog << "Write packet: pts=" << opkt.pts() << ", dts=" << opkt.dts() << " / " << opkt.pts().seconds() << " / " << opkt.timeBase() << " / st: " << opkt.streamIndex() << endl;

octx.writePacket(opkt, ec);
if (ec) {
cerr << "Error write packet: " << ec << ", " << ec.message() << endl;
return 1;
}
}
}
if (ec && ec.value() != -EAGAIN)
{
clog << "Filter pull error: " << ec << ", " << ec.message() << endl;
return 1;
}
cout << "No more frames available in filter" << endl;
}

clog << "Flush frames;\n";
while (true)
clog << "Flush frames\n";
// Push a null frame at then end for filters that
// need the full input before generating any output
// (animated GIF with a palette is one of them)
auto null_frame = VideoFrame::null();
buffer_src.addVideoFrame(null_frame, 0, ec);
// Pull until there are no more incoming frames
VideoFrame filtered;
while (buffer_sink.getVideoFrame(filtered, ec))
{
VideoFrame frame = vdec.decode(Packet(), ec);
if (ec)
{
cerr << "Error: " << ec << ", " << ec.message() << endl;
filtered.setTimeBase(encoder.timeBase());
auto ts = filtered.pts();
clog << " filtered: " << filtered.width() << "x" << filtered.height() << ", size=" << filtered.size()
<< ", ts=" << ts << ", tm: " << ts.seconds() << ", tb: " << filtered.timeBase()
<< ", ref=" << filtered.isReferenced() << ":" << filtered.refCount() << endl;

// Encode
Packet opkt = filtered ? encoder.encode(filtered, ec) : encoder.encode(ec);
if (ec) {
cerr << "Encoding error: " << ec << endl;
return 1;
}
if (!frame)
break;

// Push into the filter
buffer_src.addVideoFrame(frame, ec);
if (ec)
{
clog << "Filter push error: " << ec << ", " << ec.message() << endl;
return 1;
}
if (opkt) {
// Only one output stream
opkt.setStreamIndex(0);

// Pull until there are no more incoming frames
VideoFrame filtered;
while (buffer_sink.getVideoFrame(filtered, ec))
{
filtered.setTimeBase(frame.timeBase());
auto ts = filtered.pts();
clog << " filtered: " << filtered.width() << "x" << filtered.height() << ", size=" << filtered.size()
<< ", ts=" << ts << ", tm: " << ts.seconds() << ", tb: " << filtered.timeBase()
<< ", ref=" << filtered.isReferenced() << ":" << filtered.refCount() << endl;
}
if (ec && ec.value() != -EAGAIN)
{
clog << "Filter pull error: " << ec << ", " << ec.message() << endl;
return 1;
clog << "Write packet: pts=" << opkt.pts() << ", dts=" << opkt.dts() << " / " << opkt.pts().seconds() << " / " << opkt.timeBase() << " / st: " << opkt.streamIndex() << endl;

octx.writePacket(opkt, ec);
if (ec) {
cerr << "Error write packet: " << ec << ", " << ec.message() << endl;
return 1;
}
}
}
cout << "Filter flushed, frames: " << count << endl;
octx.writeTrailer();
}
}
1 change: 1 addition & 0 deletions example/api2-samples/meson.build
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ samples = [
'api2-decode-audio',
'api2-decode-rasample-audio',
'api2-decode-encode-audio',
'api2-decode-filter-encode',
'api2-dict-basic',
'api2-timestamp',
'api2-demux-seek',
Expand Down
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