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Add support for v4l2loopback

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It allows to send the video stream to /dev/videoN, so that it can be
captured (like a webcam) by any v4l2-capable tool.

PR #2232 <https://github.com/Genymobile/scrcpy/pull/2232>
PR #2233 <https://github.com/Genymobile/scrcpy/pull/2233>
PR #2268 <https://github.com/Genymobile/scrcpy/pull/2268>

Co-authored-by: Romain Vimont <rom@rom1v.com>
This commit is contained in:
Marco Martinelli 2021-04-04 00:10:44 +02:00 committed by Romain Vimont
parent 5af9d0ee0f
commit d39161f753
9 changed files with 480 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
app/meson.build
View file

@ -33,6 +33,11 @@ else
src += [ 'src/sys/unix/process.c' ]
endif
v4l2_support = host_machine.system() == 'linux'
if v4l2_support
src += [ 'src/v4l2_sink.c' ]
endif
check_functions = [
'strdup'
]
@ -49,6 +54,10 @@ if not get_option('crossbuild_windows')
dependency('sdl2'),
]
if v4l2_support
dependencies += dependency('libavdevice')
endif
else
# cross-compile mingw32 build (from Linux to Windows)
@ -124,6 +133,9 @@ conf.set('SERVER_DEBUGGER', get_option('server_debugger'))
# select the debugger method ('old' for Android < 9, 'new' for Android >= 9)
conf.set('SERVER_DEBUGGER_METHOD_NEW', get_option('server_debugger_method') == 'new')
# enable V4L2 support (linux only)
conf.set('HAVE_V4L2', v4l2_support)
configure_file(configuration: conf, output: 'config.h')
src_dir = include_directories('src')

6
app/scrcpy.1
View file

@ -185,6 +185,12 @@ Enable "show touches" on start, restore the initial value on exit.
It only shows physical touches (not clicks from scrcpy).
.TP
.BI "\-\-v4l2_sink " /dev/videoN
Output to v4l2loopback device.
It requires to lock the video orientation (see --lock-video-orientation).
.TP
.BI "\-V, \-\-verbosity " value
Set the log level ("debug", "info", "warn" or "error").

31
app/src/cli.c
View file

@ -176,6 +176,13 @@ scrcpy_print_usage(const char *arg0) {
" on exit.\n"
" It only shows physical touches (not clicks from scrcpy).\n"
"\n"
#ifdef HAVE_V4L2
" --v4l2_sink /dev/videoN\n"
" Output to v4l2loopback device.\n"
" It requires to lock the video orientation (see\n"
" --lock-video-orientation).\n"
"\n"
#endif
" -V, --verbosity value\n"
" Set the log level (debug, info, warn or error).\n"
#ifndef NDEBUG
@ -676,6 +683,7 @@ guess_record_format(const char *filename) {
#define OPT_LEGACY_PASTE 1024
#define OPT_ENCODER_NAME 1025
#define OPT_POWER_OFF_ON_CLOSE 1026
#define OPT_V4L2_SINK 1027
bool
scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]) {
@ -717,6 +725,9 @@ scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]) {
{"show-touches", no_argument, NULL, 't'},
{"stay-awake", no_argument, NULL, 'w'},
{"turn-screen-off", no_argument, NULL, 'S'},
#ifdef HAVE_V4L2
{"v4l2_sink", required_argument, NULL, OPT_V4L2_SINK},
#endif
{"verbosity", required_argument, NULL, 'V'},
{"version", no_argument, NULL, 'v'},
{"window-title", required_argument, NULL, OPT_WINDOW_TITLE},
@ -901,16 +912,36 @@ scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]) {
case OPT_POWER_OFF_ON_CLOSE:
opts->power_off_on_close = true;
break;
#ifdef HAVE_V4L2
case OPT_V4L2_SINK:
opts->v4l2_device = optarg;
break;
#endif
default:
// getopt prints the error message on stderr
return false;
}
}
#ifdef HAVE_V4L2
if (!opts->display && !opts->record_filename && !opts->v4l2_device) {
LOGE("-N/--no-display requires either screen recording (-r/--record)"
" or sink to v4l2loopback device (--v4l2_sink)");
return false;
}
if (opts->v4l2_device && opts->lock_video_orientation
== SC_LOCK_VIDEO_ORIENTATION_UNLOCKED) {
LOGI("Video orientation is locked for v4l2 sink. "
"See --lock-video-orientation.");
opts->lock_video_orientation = SC_LOCK_VIDEO_ORIENTATION_INITIAL;
}
#else
if (!opts->display && !opts->record_filename) {
LOGE("-N/--no-display requires screen recording (-r/--record)");
return false;
}
#endif
int index = optind;
if (index < argc) {

2
app/src/decoder.h
View file

@ -8,7 +8,7 @@
#include <stdbool.h>
#include <libavformat/avformat.h>
#define DECODER_MAX_SINKS 1
#define DECODER_MAX_SINKS 2
struct decoder {
struct sc_packet_sink packet_sink; // packet sink trait

14
app/src/main.c
View file

@ -6,6 +6,9 @@
#include <stdbool.h>
#include <unistd.h>
#include <libavformat/avformat.h>
#ifdef HAVE_V4L2
# include <libavdevice/avdevice.h>
#endif
#define SDL_MAIN_HANDLED // avoid link error on Linux Windows Subsystem
#include <SDL2/SDL.h>
@ -28,6 +31,11 @@ print_version(void) {
fprintf(stderr, " - libavutil %d.%d.%d\n", LIBAVUTIL_VERSION_MAJOR,
LIBAVUTIL_VERSION_MINOR,
LIBAVUTIL_VERSION_MICRO);
#ifdef HAVE_V4L2
fprintf(stderr, " - libavdevice %d.%d.%d\n", LIBAVDEVICE_VERSION_MAJOR,
LIBAVDEVICE_VERSION_MINOR,
LIBAVDEVICE_VERSION_MICRO);
#endif
}
static SDL_LogPriority
@ -90,6 +98,12 @@ main(int argc, char *argv[]) {
av_register_all();
#endif
#ifdef HAVE_V4L2
if (args.opts.v4l2_device) {
avdevice_register_all();
}
#endif
if (avformat_network_init()) {
return 1;
}

35
app/src/scrcpy.c
View file

@ -27,6 +27,9 @@
#include "tiny_xpm.h"
#include "util/log.h"
#include "util/net.h"
#ifdef HAVE_V4L2
# include "v4l2_sink.h"
#endif
static struct server server;
static struct screen screen;
@ -34,6 +37,9 @@ static struct fps_counter fps_counter;
static struct stream stream;
static struct decoder decoder;
static struct recorder recorder;
#ifdef HAVE_V4L2
static struct sc_v4l2_sink v4l2_sink;
#endif
static struct controller controller;
static struct file_handler file_handler;
@ -247,6 +253,9 @@ scrcpy(const struct scrcpy_options *options) {
bool fps_counter_initialized = false;
bool file_handler_initialized = false;
bool recorder_initialized = false;
#ifdef HAVE_V4L2
bool v4l2_sink_initialized = false;
#endif
bool stream_started = false;
bool controller_initialized = false;
bool controller_started = false;
@ -295,7 +304,6 @@ scrcpy(const struct scrcpy_options *options) {
goto end;
}
struct decoder *dec = NULL;
if (options->display) {
if (!fps_counter_init(&fps_counter)) {
goto end;
@ -309,7 +317,14 @@ scrcpy(const struct scrcpy_options *options) {
}
file_handler_initialized = true;
}
}
struct decoder *dec = NULL;
bool needs_decoder = options->display;
#ifdef HAVE_V4L2
needs_decoder |= !!options->v4l2_device;
#endif
if (needs_decoder) {
decoder_init(&decoder);
dec = &decoder;
}
@ -386,6 +401,18 @@ scrcpy(const struct scrcpy_options *options) {
}
}
#ifdef HAVE_V4L2
if (options->v4l2_device) {
if (!sc_v4l2_sink_init(&v4l2_sink, options->v4l2_device, frame_size)) {
goto end;
}
decoder_add_sink(&decoder, &v4l2_sink.frame_sink);
v4l2_sink_initialized = true;
}
#endif
// now we consumed the header values, the socket receives the video stream
// start the stream
if (!stream_start(&stream)) {
@ -426,6 +453,12 @@ end:
stream_join(&stream);
}
#ifdef HAVE_V4L2
if (v4l2_sink_initialized) {
sc_v4l2_sink_destroy(&v4l2_sink);
}
#endif
// Destroy the screen only after the stream is guaranteed to be finished,
// because otherwise the screen could receive new frames after destruction
if (screen_initialized) {

2
app/src/scrcpy.h
View file

@ -62,6 +62,7 @@ struct scrcpy_options {
const char *render_driver;
const char *codec_options;
const char *encoder_name;
const char *v4l2_device;
enum sc_log_level log_level;
enum sc_record_format record_format;
struct sc_port_range port_range;
@ -103,6 +104,7 @@ struct scrcpy_options {
.render_driver = NULL, \
.codec_options = NULL, \
.encoder_name = NULL, \
.v4l2_device = NULL, \
.log_level = SC_LOG_LEVEL_INFO, \
.record_format = SC_RECORD_FORMAT_AUTO, \
.port_range = { \

341
app/src/v4l2_sink.c Normal file
View file

@ -0,0 +1,341 @@
#include "v4l2_sink.h"
#include "util/log.h"
#include "util/str_util.h"
/** Downcast frame_sink to sc_v4l2_sink */
#define DOWNCAST(SINK) container_of(SINK, struct sc_v4l2_sink, frame_sink)
static const AVRational SCRCPY_TIME_BASE = {1, 1000000}; // timestamps in us
static const AVOutputFormat *
find_muxer(const char *name) {
#ifdef SCRCPY_LAVF_HAS_NEW_MUXER_ITERATOR_API
void *opaque = NULL;
#endif
const AVOutputFormat *oformat = NULL;
do {
#ifdef SCRCPY_LAVF_HAS_NEW_MUXER_ITERATOR_API
oformat = av_muxer_iterate(&opaque);
#else
oformat = av_oformat_next(oformat);
#endif
// until null or containing the requested name
} while (oformat && !strlist_contains(oformat->name, ',', name));
return oformat;
}
static bool
write_header(struct sc_v4l2_sink *vs, const AVPacket *packet) {
AVStream *ostream = vs->format_ctx->streams[0];
uint8_t *extradata = av_malloc(packet->size * sizeof(uint8_t));
if (!extradata) {
LOGC("Could not allocate extradata");
return false;
}
// copy the first packet to the extra data
memcpy(extradata, packet->data, packet->size);
ostream->codecpar->extradata = extradata;
ostream->codecpar->extradata_size = packet->size;
int ret = avformat_write_header(vs->format_ctx, NULL);
if (ret < 0) {
LOGE("Failed to write header to %s", vs->device_name);
return false;
}
return true;
}
static void
rescale_packet(struct sc_v4l2_sink *vs, AVPacket *packet) {
AVStream *ostream = vs->format_ctx->streams[0];
av_packet_rescale_ts(packet, SCRCPY_TIME_BASE, ostream->time_base);
}
static bool
write_packet(struct sc_v4l2_sink *vs, AVPacket *packet) {
if (!vs->header_written) {
bool ok = write_header(vs, packet);
if (!ok) {
return false;
}
vs->header_written = true;
return true;
}
rescale_packet(vs, packet);
bool ok = av_write_frame(vs->format_ctx, packet) >= 0;
// Failing to write the last frame is not very serious, no future frame may
// depend on it, so the resulting file will still be valid
(void) ok;
return true;
}
static bool
encode_and_write_frame(struct sc_v4l2_sink *vs, const AVFrame *frame) {
int ret = avcodec_send_frame(vs->encoder_ctx, frame);
if (ret < 0 && ret != AVERROR(EAGAIN)) {
LOGE("Could not send v4l2 video frame: %d", ret);
return false;
}
AVPacket *packet = &vs->packet;
ret = avcodec_receive_packet(vs->encoder_ctx, packet);
if (ret == 0) {
// A packet was received
bool ok = write_packet(vs, packet);
if (!ok) {
LOGW("Could not send packet to v4l2 sink");
return false;
}
av_packet_unref(packet);
} else if (ret != AVERROR(EAGAIN)) {
LOGE("Could not receive v4l2 video packet: %d", ret);
return false;
}
return true;
}
static int
run_v4l2_sink(void *data) {
struct sc_v4l2_sink *vs = data;
for (;;) {
sc_mutex_lock(&vs->mutex);
while (!vs->stopped && vs->vb.pending_frame_consumed) {
sc_cond_wait(&vs->cond, &vs->mutex);
}
if (vs->stopped) {
sc_mutex_unlock(&vs->mutex);
break;
}
sc_mutex_unlock(&vs->mutex);
video_buffer_consume(&vs->vb, vs->frame);
bool ok = encode_and_write_frame(vs, vs->frame);
if (!ok) {
LOGE("Could not send frame to v4l2 sink");
break;
}
}
LOGD("V4l2 thread ended");
return 0;
}
static bool
sc_v4l2_sink_open(struct sc_v4l2_sink *vs) {
bool ok = video_buffer_init(&vs->vb);
if (!ok) {
return false;
}
ok = sc_mutex_init(&vs->mutex);
if (!ok) {
LOGC("Could not create mutex");
goto error_video_buffer_destroy;
}
ok = sc_cond_init(&vs->cond);
if (!ok) {
LOGC("Could not create cond");
goto error_mutex_destroy;
}
// FIXME
const AVOutputFormat *format = find_muxer("video4linux2,v4l2");
if (!format) {
LOGE("Could not find v4l2 muxer");
goto error_cond_destroy;
}
const AVCodec *encoder = avcodec_find_encoder(AV_CODEC_ID_RAWVIDEO);
if (!encoder) {
LOGE("Raw video encoder not found");
return false;
}
vs->format_ctx = avformat_alloc_context();
if (!vs->format_ctx) {
LOGE("Could not allocate v4l2 output context");
return false;
}
// contrary to the deprecated API (av_oformat_next()), av_muxer_iterate()
// returns (on purpose) a pointer-to-const, but AVFormatContext.oformat
// still expects a pointer-to-non-const (it has not be updated accordingly)
// <https://github.com/FFmpeg/FFmpeg/commit/0694d8702421e7aff1340038559c438b61bb30dd>
vs->format_ctx->oformat = (AVOutputFormat *) format;
vs->format_ctx->url = strdup(vs->device_name);
if (!vs->format_ctx->url) {
LOGE("Could not strdup v4l2 device name");
goto error_avformat_free_context;
return false;
}
AVStream *ostream = avformat_new_stream(vs->format_ctx, encoder);
if (!ostream) {
LOGE("Could not allocate new v4l2 stream");
goto error_avformat_free_context;
return false;
}
ostream->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
ostream->codecpar->codec_id = encoder->id;
ostream->codecpar->format = AV_PIX_FMT_YUV420P;
ostream->codecpar->width = vs->frame_size.width;
ostream->codecpar->height = vs->frame_size.height;
int ret = avio_open(&vs->format_ctx->pb, vs->device_name, AVIO_FLAG_WRITE);
if (ret < 0) {
LOGE("Failed to open output device: %s", vs->device_name);
// ostream will be cleaned up during context cleaning
goto error_avformat_free_context;
}
vs->encoder_ctx = avcodec_alloc_context3(encoder);
if (!vs->encoder_ctx) {
LOGC("Could not allocate codec context for v4l2");
goto error_avio_close;
}
vs->encoder_ctx->width = vs->frame_size.width;
vs->encoder_ctx->height = vs->frame_size.height;
vs->encoder_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
vs->encoder_ctx->time_base.num = 1;
vs->encoder_ctx->time_base.den = 1;
if (avcodec_open2(vs->encoder_ctx, encoder, NULL) < 0) {
LOGE("Could not open codec for v4l2");
goto error_avcodec_free_context;
}
vs->frame = av_frame_alloc();
if (!vs->frame) {
LOGE("Could not create v4l2 frame");
goto error_avcodec_close;
}
LOGD("Starting v4l2 thread");
ok = sc_thread_create(&vs->thread, run_v4l2_sink, "v4l2", vs);
if (!ok) {
LOGC("Could not start v4l2 thread");
goto error_av_frame_free;
}
vs->header_written = false;
vs->stopped = false;
LOGI("v4l2 sink started to device: %s", vs->device_name);
return true;
error_av_frame_free:
av_frame_free(&vs->frame);
error_avcodec_close:
avcodec_close(vs->encoder_ctx);
error_avcodec_free_context:
avcodec_free_context(&vs->encoder_ctx);
error_avio_close:
avio_close(vs->format_ctx->pb);
error_avformat_free_context:
avformat_free_context(vs->format_ctx);
error_cond_destroy:
sc_cond_destroy(&vs->cond);
error_mutex_destroy:
sc_mutex_destroy(&vs->mutex);
error_video_buffer_destroy:
video_buffer_destroy(&vs->vb);
return false;
}
static void
sc_v4l2_sink_close(struct sc_v4l2_sink *vs) {
sc_mutex_lock(&vs->mutex);
vs->stopped = true;
sc_cond_signal(&vs->cond);
sc_mutex_unlock(&vs->mutex);
sc_thread_join(&vs->thread, NULL);
av_frame_free(&vs->frame);
avcodec_close(vs->encoder_ctx);
avcodec_free_context(&vs->encoder_ctx);
avio_close(vs->format_ctx->pb);
avformat_free_context(vs->format_ctx);
sc_cond_destroy(&vs->cond);
sc_mutex_destroy(&vs->mutex);
video_buffer_destroy(&vs->vb);
}
static bool
sc_v4l2_sink_push(struct sc_v4l2_sink *vs, const AVFrame *frame) {
bool ok = video_buffer_push(&vs->vb, frame, NULL);
if (!ok) {
return false;
}
// signal possible change of vs->vb.pending_frame_consumed
sc_cond_signal(&vs->cond);
return true;
}
static bool
sc_v4l2_frame_sink_open(struct sc_frame_sink *sink) {
struct sc_v4l2_sink *vs = DOWNCAST(sink);
return sc_v4l2_sink_open(vs);
}
static void
sc_v4l2_frame_sink_close(struct sc_frame_sink *sink) {
struct sc_v4l2_sink *vs = DOWNCAST(sink);
sc_v4l2_sink_close(vs);
}
static bool
sc_v4l2_frame_sink_push(struct sc_frame_sink *sink, const AVFrame *frame) {
struct sc_v4l2_sink *vs = DOWNCAST(sink);
return sc_v4l2_sink_push(vs, frame);
}
bool
sc_v4l2_sink_init(struct sc_v4l2_sink *vs, const char *device_name,
struct size frame_size) {
vs->device_name = strdup(device_name);
if (!vs->device_name) {
LOGE("Could not strdup v4l2 device name");
return false;
}
vs->frame_size = frame_size;
static const struct sc_frame_sink_ops ops = {
.open = sc_v4l2_frame_sink_open,
.close = sc_v4l2_frame_sink_close,
.push = sc_v4l2_frame_sink_push,
};
vs->frame_sink.ops = &ops;
return true;
}
void
sc_v4l2_sink_destroy(struct sc_v4l2_sink *vs) {
free(vs->device_name);
}

39
app/src/v4l2_sink.h Normal file
View file

@ -0,0 +1,39 @@
#ifndef SC_V4L2_SINK_H
#define SC_V4L2_SINK_H
#include "common.h"
#include "coords.h"
#include "trait/frame_sink.h"
#include "video_buffer.h"
#include <libavformat/avformat.h>
struct sc_v4l2_sink {
struct sc_frame_sink frame_sink; // frame sink trait
struct video_buffer vb;
AVFormatContext *format_ctx;
AVCodecContext *encoder_ctx;
char *device_name;
struct size frame_size;
sc_thread thread;
sc_mutex mutex;
sc_cond cond;
bool stopped;
bool header_written;
AVFrame *frame;
AVPacket packet;
};
bool
sc_v4l2_sink_init(struct sc_v4l2_sink *vs, const char *device_name,
struct size frame_size);
void
sc_v4l2_sink_destroy(struct sc_v4l2_sink *vs);
#endif