Add FormatContext::streams()

Author: h4tr3d

example/api2-samples/api2-decode.cpp

@@ -58,11 +58,10 @@ int main(int argc, char **argv)
             return 1;
         }
 
-        for (size_t i = 0; i < ictx.streamsCount(); ++i) {
-            auto st = ictx.stream(i);
+        for (auto&& st : ictx.streams()) {
             if (st.mediaType() == AVMEDIA_TYPE_VIDEO) {
-                videoStream = i;
                 vst = st;
+                videoStream = st.index();
                 break;
             }
         }

src/avcpp/formatcontext.cpp

@@ -300,6 +300,14 @@ Stream FormatContext::addStream(const AudioEncoderContext &encCtx, OptionalError
     return addStream(static_cast<const CodecContext2&>(encCtx), ec);
 }
 
+FormatContext::StreamsView FormatContext::streams(OptionalErrorCode ec) const {
+    if (!m_raw || !m_raw->streams || !m_raw->nb_streams) {
+        throws_if(ec, Errors::Unallocated);
+        return {};
+    }
+    return std::span(m_raw->streams, m_raw->nb_streams) | std::views::transform(_StreamTransform{this});
+}
+
 bool FormatContext::seekable() const noexcept
 {
     if (m_raw && m_raw->pb) {

src/avcpp/formatcontext.h

@@ -53,6 +53,17 @@ struct CustomIO
 
 class FormatContext : public FFWrapperPtr<AVFormatContext>, public noncopyable
 {
+#if AVCPP_CXX_STANDARD >= 20
+    struct _StreamTransform {
+        const FormatContext *_parent{};
+        Stream operator()(AVStream *st) const {
+            assert(_parent);
+            return Stream{_parent->m_monitor, st, _parent->isOutput() ? Direction::Encoding : Direction::Decoding};
+        }
+    };
+    using StreamsView = std::ranges::transform_view<std::span<AVStream*>, _StreamTransform>;
+#endif
+
 public:
     FormatContext();
     ~FormatContext();
@@ -85,6 +96,10 @@ class FormatContext : public FFWrapperPtr<AVFormatContext>, public noncopyable
     Stream addStream(const class VideoEncoderContext& encCtx, OptionalErrorCode ec = throws());
     Stream addStream(const class AudioEncoderContext& encCtx, OptionalErrorCode ec = throws());
 
+#if AVCPP_CXX_STANDARD >= 20
+    StreamsView streams(OptionalErrorCode ec = throws()) const;
+#endif
+
     //
     // Seeking
     //