API and example for printing a session's SDP

This is useful for debugging.

README.md

@@ -78,9 +78,9 @@ $ cargo run --example client <CMD>
 
 Where CMD:
 
-* **info** - Get info about available streams and exit
-* **mp4** - Write RTSP streams to mp4 file, exit with Ctrl+C
-* **metadata** - Get realtime onvif metadata if available, exit with Ctrl+C
+* **info** - Gets info about available streams and exits.
+* **mp4** - Writes RTSP streams to mp4 file; exit with Ctrl+C.
+* **metadata** - Gets realtime onvif metadata if available; exit with Ctrl+C.
 
 ## Acknowledgements
 

examples/client/info.rs

@@ -0,0 +1,43 @@
+// Copyright (C) 2022 Scott Lamb <slamb@slamb.org>
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+//! Gets info about available streams and exits.
+
+use anyhow::Error;
+
+#[derive(structopt::StructOpt)]
+pub struct Opts {
+    #[structopt(flatten)]
+    src: super::Source,
+
+    /// Prints the SDP (Session Description Protocol) session description.
+    #[structopt(long)]
+    print_sdp: bool,
+
+    /// Prints debug output for each decoded stream.
+    #[structopt(long)]
+    print_streams: bool,
+}
+
+pub async fn run(opts: Opts) -> Result<(), Error> {
+    let creds = super::creds(opts.src.username.clone(), opts.src.password.clone());
+    let session = retina::client::Session::describe(
+        opts.src.url.clone(),
+        retina::client::SessionOptions::default()
+            .creds(creds)
+            .user_agent("Retina sdp example".to_owned()),
+    )
+    .await?;
+    if opts.print_sdp {
+        println!("SDP:\n{}\n\n", std::str::from_utf8(session.sdp())?);
+    }
+    if opts.print_streams {
+        for (i, stream) in session.streams().iter().enumerate() {
+            println!("stream {}:\n{:#?}\n\n", i, stream);
+        }
+    }
+    if !opts.print_sdp && !opts.print_streams {
+        eprintln!("You probably wanted at least one of --print-sdp or --print-streams?");
+    }
+    Ok(())
+}

examples/client/main.rs

@@ -3,8 +3,9 @@
 
 //! RTSP client examples.
 
-mod metadata;
+mod info;
 mod mp4;
+mod onvif;
 
 use anyhow::Error;
 use log::{error, info};
@@ -28,12 +29,12 @@ struct Source {
 
 #[derive(StructOpt)]
 enum Cmd {
-    /// Write available audio and video streams to mp4 file
+    /// Gets info about available streams and exits.
+    Info(info::Opts),
+    /// Writes available audio and video streams to mp4 file; use Ctrl+C to stop.
     Mp4(mp4::Opts),
-    /// Get realtime metadata of onvif stream, use Ctrl+C to stop
-    Metadata(metadata::Opts),
-    /// Get info about available streams and exit
-    Info(metadata::Opts),
+    /// Follows ONVIF metadata stream; use Ctrl+C to stop.
+    Onvif(onvif::Opts),
 }
 
 fn init_logging() -> mylog::Handle {
@@ -81,8 +82,8 @@ fn creds(
 async fn main_inner() -> Result<(), Error> {
     let cmd = Cmd::from_args();
     match cmd {
+        Cmd::Info(opts) => info::run(opts).await,
         Cmd::Mp4(opts) => mp4::run(opts).await,
-        Cmd::Metadata(opts) => metadata::run(opts, false).await,
-        Cmd::Info(opts) => metadata::run(opts, true).await,
+        Cmd::Onvif(opts) => onvif::run(opts).await,
     }
 }

examples/client/onvif.rs

@@ -14,20 +14,16 @@ pub struct Opts {
     src: super::Source,
 }
 
-pub async fn run(opts: Opts, is_info: bool) -> Result<(), Error> {
+pub async fn run(opts: Opts) -> Result<(), Error> {
     let session_group = Arc::new(SessionGroup::default());
-    let r = run_inner(opts, session_group.clone(), is_info).await;
+    let r = run_inner(opts, session_group.clone()).await;
     if let Err(e) = session_group.await_teardown().await {
         error!("TEARDOWN failed: {}", e);
     }
     r
 }
 
-async fn run_inner(
-    opts: Opts,
-    session_group: Arc<SessionGroup>,
-    is_info: bool,
-) -> Result<(), Error> {
+async fn run_inner(opts: Opts, session_group: Arc<SessionGroup>) -> Result<(), Error> {
     let stop = tokio::signal::ctrl_c();
 
     let creds = super::creds(opts.src.username, opts.src.password);
@@ -39,12 +35,6 @@ async fn run_inner(
             .session_group(session_group),
     )
     .await?;
-    if is_info {
-        for stream in session.streams() {
-            println!("{:#?}", stream);
-        }
-        return Ok(());
-    }
     let onvif_stream_i = session
         .streams()
         .iter()

src/client/mod.rs

@@ -758,7 +758,9 @@ pub trait State {}
 
 /// Initial state after a `DESCRIBE`; use via `Session<Described>`.
 #[doc(hidden)]
-pub struct Described(());
+pub struct Described {
+    sdp: Bytes,
+}
 impl State for Described {}
 
 enum KeepaliveState {
@@ -1127,6 +1129,8 @@ impl Session<Described> {
                 description,
             })
         })?;
+        let describe_status = response.status();
+        let sdp = response.into_body();
         Ok(Session(
             Box::pin(SessionInner {
                 conn: Some(conn),
@@ -1137,16 +1141,25 @@ impl Session<Described> {
                 session: None,
                 describe_ctx: msg_ctx,
                 describe_cseq: cseq,
-                describe_status: response.status(),
+                describe_status,
                 keepalive_state: KeepaliveState::Idle,
                 keepalive_timer: None,
                 maybe_playing: false,
                 udp_next_poll_i: 0,
             }),
-            Described(()),
+            Described { sdp },
         ))
     }
 
+    /// Returns the raw SDP (Session Description Protocol) session description of this URL.
+    ///
+    /// Retina interprets the SDP automatically, but the raw bytes may be useful for debugging.
+    /// They're accessibled in the `Session<Described>` state. Currently, they're discarded on
+    /// `play` to reduce memory usage.
+    pub fn sdp(&self) -> &[u8] {
+        &self.1.sdp
+    }
+
     /// Sends a `SETUP` request for a stream.
     ///
     /// Note these can't reasonably be pipelined because subsequent requests