diff mbox

[FFmpeg-devel,4/4] avcodec/mediacodecdec: restructure mediacodec_receive_frame

Message ID 20180424205926.42027-4-ffmpeg@tmm1.net
State Superseded
Headers show

Commit Message

Aman Gupta April 24, 2018, 8:59 p.m. UTC
From: Aman Gupta <aman@tmm1.net>

This fixes issues reported on some devices where both
avcodec_send_packet and avcodec_receive_frame can return EAGAIN
at the same time, instead of one or the other blocking.

The new logic follows a recommendation by @rcombs to use
dequeueInputBuffer with a timeout of 0 as a way to detect
whether the codec wants more data. The dequeued buffer index is
kept in MediaCodecDecContext until it can be used next.

A similar technique is also used by the Google's official media
player Exoplayer: see MediaCodecRenderer.feedInputBuffer().
---
 libavcodec/mediacodecdec.c        | 78 ++++++++++++++++++++-------------------
 libavcodec/mediacodecdec_common.c | 28 ++++++++------
 libavcodec/mediacodecdec_common.h |  4 +-
 3 files changed, 59 insertions(+), 51 deletions(-)

Comments

Matthieu Bouron April 26, 2018, 10:45 a.m. UTC | #1
On Tue, Apr 24, 2018 at 01:59:26PM -0700, Aman Gupta wrote:
> From: Aman Gupta <aman@tmm1.net>
> 
> This fixes issues reported on some devices where both
> avcodec_send_packet and avcodec_receive_frame can return EAGAIN
> at the same time, instead of one or the other blocking.
> 
> The new logic follows a recommendation by @rcombs to use
> dequeueInputBuffer with a timeout of 0 as a way to detect
> whether the codec wants more data. The dequeued buffer index is
> kept in MediaCodecDecContext until it can be used next.
> 
> A similar technique is also used by the Google's official media
> player Exoplayer: see MediaCodecRenderer.feedInputBuffer().
> ---
>  libavcodec/mediacodecdec.c        | 78 ++++++++++++++++++++-------------------
>  libavcodec/mediacodecdec_common.c | 28 ++++++++------
>  libavcodec/mediacodecdec_common.h |  4 +-
>  3 files changed, 59 insertions(+), 51 deletions(-)
> 
> diff --git a/libavcodec/mediacodecdec.c b/libavcodec/mediacodecdec.c
> index e5d3e6a0af..1a681d771e 100644
> --- a/libavcodec/mediacodecdec.c
> +++ b/libavcodec/mediacodecdec.c
> @@ -391,33 +391,11 @@ done:
>      return ret;
>  }
>  
> -static int mediacodec_send_receive(AVCodecContext *avctx,
> -                                   MediaCodecH264DecContext *s,
> -                                   AVFrame *frame, bool wait)
> -{
> -    int ret;
> -
> -    /* send any pending data from buffered packet */
> -    while (s->buffered_pkt.size) {
> -        ret = ff_mediacodec_dec_send(avctx, s->ctx, &s->buffered_pkt);
> -        if (ret == AVERROR(EAGAIN))
> -            break;
> -        else if (ret < 0)
> -            return ret;
> -        s->buffered_pkt.size -= ret;
> -        s->buffered_pkt.data += ret;
> -        if (s->buffered_pkt.size <= 0)
> -            av_packet_unref(&s->buffered_pkt);
> -    }
> -
> -    /* check for new frame */
> -    return ff_mediacodec_dec_receive(avctx, s->ctx, frame, wait);
> -}
> -
>  static int mediacodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
>  {
>      MediaCodecH264DecContext *s = avctx->priv_data;
>      int ret;
> +    ssize_t index;
>  
>      /* in delay_flush mode, wait until the user has released or rendered
>         all retained frames. */
> @@ -427,28 +405,52 @@ static int mediacodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
>          }
>      }
>  
> -    /* flush buffered packet and check for new frame */
> -    ret = mediacodec_send_receive(avctx, s, frame, false);
> +    /* poll for new frame */
> +    ret = ff_mediacodec_dec_receive(avctx, s->ctx, frame, false);
>      if (ret != AVERROR(EAGAIN))
>          return ret;
>  
> -    /* skip fetching new packet if we still have one buffered */
> -    if (s->buffered_pkt.size > 0)
> -        return mediacodec_send_receive(avctx, s, frame, true);
> +    /* feed decoder */
> +    while (1) {
> +        if (s->ctx->current_input_buffer < 0) {
> +            /* poll for input space */
> +            index = ff_AMediaCodec_dequeueInputBuffer(s->ctx->codec, 0);
> +            if (index < 0) {
> +                /* no space, wait a while for an output frame to appear */
> +                return ff_mediacodec_dec_receive(avctx, s->ctx, frame, true);
> +            }
> +            s->ctx->current_input_buffer = index;
> +        }
>  
> -    /* fetch new packet or eof */
> -    ret = ff_decode_get_packet(avctx, &s->buffered_pkt);
> -    if (ret == AVERROR_EOF) {
> -        AVPacket null_pkt = { 0 };
> -        ret = ff_mediacodec_dec_send(avctx, s->ctx, &null_pkt);
> -        if (ret < 0)
> +        /* try to flush any buffered packet data */
> +        if (s->buffered_pkt.size > 0) {
> +            ret = ff_mediacodec_dec_send(avctx, s->ctx, &s->buffered_pkt, false);
> +            if (ret > 0) {
> +                s->buffered_pkt.size -= ret;
> +                s->buffered_pkt.data += ret;
> +                if (s->buffered_pkt.size <= 0)
> +                    av_packet_unref(&s->buffered_pkt);
> +            } else if (ret < 0 && ret == AVERROR(EAGAIN)) {
> +                return ret;
> +            }
> +            continue;
> +        }
> +
> +        /* fetch new packet or eof */
> +        ret = ff_decode_get_packet(avctx, &s->buffered_pkt);
> +        if (ret == AVERROR_EOF) {
> +            AVPacket null_pkt = { 0 };
> +            ret = ff_mediacodec_dec_send(avctx, s->ctx, &null_pkt, true);
> +            if (ret < 0)
> +                return ret;
> +        }
> +        else if (ret == AVERROR(EAGAIN) && s->ctx->current_input_buffer < 0)
> +            return ff_mediacodec_dec_receive(avctx, s->ctx, frame, true);

If the input is starved on the FFmpeg side, we shouldn't block on trying
to receive a new frame from MediaCodec as it causes a performance
regression while the decoder is still not buffered enough to output its
first frame (after init or after a flush) as the function will end up
waiting 8ms for each new packet (for each call to avcodec_send_packet()).

Returning directly EAGAIN from here is fine as we will end up calling
ff_mediacodec_dec_receive() from the next call to avcodec_send_packet() or
avcodec_receive_frame().

With this modification the patch works fine on my devices without any
performance regression.

[...]
diff mbox

Patch

diff --git a/libavcodec/mediacodecdec.c b/libavcodec/mediacodecdec.c
index e5d3e6a0af..1a681d771e 100644
--- a/libavcodec/mediacodecdec.c
+++ b/libavcodec/mediacodecdec.c
@@ -391,33 +391,11 @@  done:
     return ret;
 }
 
-static int mediacodec_send_receive(AVCodecContext *avctx,
-                                   MediaCodecH264DecContext *s,
-                                   AVFrame *frame, bool wait)
-{
-    int ret;
-
-    /* send any pending data from buffered packet */
-    while (s->buffered_pkt.size) {
-        ret = ff_mediacodec_dec_send(avctx, s->ctx, &s->buffered_pkt);
-        if (ret == AVERROR(EAGAIN))
-            break;
-        else if (ret < 0)
-            return ret;
-        s->buffered_pkt.size -= ret;
-        s->buffered_pkt.data += ret;
-        if (s->buffered_pkt.size <= 0)
-            av_packet_unref(&s->buffered_pkt);
-    }
-
-    /* check for new frame */
-    return ff_mediacodec_dec_receive(avctx, s->ctx, frame, wait);
-}
-
 static int mediacodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
 {
     MediaCodecH264DecContext *s = avctx->priv_data;
     int ret;
+    ssize_t index;
 
     /* in delay_flush mode, wait until the user has released or rendered
        all retained frames. */
@@ -427,28 +405,52 @@  static int mediacodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
         }
     }
 
-    /* flush buffered packet and check for new frame */
-    ret = mediacodec_send_receive(avctx, s, frame, false);
+    /* poll for new frame */
+    ret = ff_mediacodec_dec_receive(avctx, s->ctx, frame, false);
     if (ret != AVERROR(EAGAIN))
         return ret;
 
-    /* skip fetching new packet if we still have one buffered */
-    if (s->buffered_pkt.size > 0)
-        return mediacodec_send_receive(avctx, s, frame, true);
+    /* feed decoder */
+    while (1) {
+        if (s->ctx->current_input_buffer < 0) {
+            /* poll for input space */
+            index = ff_AMediaCodec_dequeueInputBuffer(s->ctx->codec, 0);
+            if (index < 0) {
+                /* no space, wait a while for an output frame to appear */
+                return ff_mediacodec_dec_receive(avctx, s->ctx, frame, true);
+            }
+            s->ctx->current_input_buffer = index;
+        }
 
-    /* fetch new packet or eof */
-    ret = ff_decode_get_packet(avctx, &s->buffered_pkt);
-    if (ret == AVERROR_EOF) {
-        AVPacket null_pkt = { 0 };
-        ret = ff_mediacodec_dec_send(avctx, s->ctx, &null_pkt);
-        if (ret < 0)
+        /* try to flush any buffered packet data */
+        if (s->buffered_pkt.size > 0) {
+            ret = ff_mediacodec_dec_send(avctx, s->ctx, &s->buffered_pkt, false);
+            if (ret > 0) {
+                s->buffered_pkt.size -= ret;
+                s->buffered_pkt.data += ret;
+                if (s->buffered_pkt.size <= 0)
+                    av_packet_unref(&s->buffered_pkt);
+            } else if (ret < 0 && ret == AVERROR(EAGAIN)) {
+                return ret;
+            }
+            continue;
+        }
+
+        /* fetch new packet or eof */
+        ret = ff_decode_get_packet(avctx, &s->buffered_pkt);
+        if (ret == AVERROR_EOF) {
+            AVPacket null_pkt = { 0 };
+            ret = ff_mediacodec_dec_send(avctx, s->ctx, &null_pkt, true);
+            if (ret < 0)
+                return ret;
+        }
+        else if (ret == AVERROR(EAGAIN) && s->ctx->current_input_buffer < 0)
+            return ff_mediacodec_dec_receive(avctx, s->ctx, frame, true);
+        else if (ret < 0)
             return ret;
     }
-    else if (ret < 0)
-        return ret;
 
-    /* crank decoder with new packet */
-    return mediacodec_send_receive(avctx, s, frame, true);
+    return AVERROR(EAGAIN);
 }
 
 static void mediacodec_decode_flush(AVCodecContext *avctx)
diff --git a/libavcodec/mediacodecdec_common.c b/libavcodec/mediacodecdec_common.c
index c0f0a6b983..887865a281 100644
--- a/libavcodec/mediacodecdec_common.c
+++ b/libavcodec/mediacodecdec_common.c
@@ -450,6 +450,7 @@  static int mediacodec_dec_flush_codec(AVCodecContext *avctx, MediaCodecDecContex
     s->eos = 0;
     atomic_fetch_add(&s->serial, 1);
     atomic_init(&s->hw_buffer_count, 0);
+    s->current_input_buffer = -1;
 
     status = ff_AMediaCodec_flush(codec);
     if (status < 0) {
@@ -477,6 +478,7 @@  int ff_mediacodec_dec_init(AVCodecContext *avctx, MediaCodecDecContext *s,
     atomic_init(&s->refcount, 1);
     atomic_init(&s->hw_buffer_count, 0);
     atomic_init(&s->serial, 1);
+    s->current_input_buffer = -1;
 
     pix_fmt = ff_get_format(avctx, pix_fmts);
     if (pix_fmt == AV_PIX_FMT_MEDIACODEC) {
@@ -561,16 +563,16 @@  fail:
 }
 
 int ff_mediacodec_dec_send(AVCodecContext *avctx, MediaCodecDecContext *s,
-                           AVPacket *pkt)
+                           AVPacket *pkt, bool wait)
 {
     int offset = 0;
     int need_draining = 0;
     uint8_t *data;
-    ssize_t index;
+    ssize_t index = s->current_input_buffer;
     size_t size;
     FFAMediaCodec *codec = s->codec;
     int status;
-    int64_t input_dequeue_timeout_us = INPUT_DEQUEUE_TIMEOUT_US;
+    int64_t input_dequeue_timeout_us = wait ? INPUT_DEQUEUE_TIMEOUT_US : 0;
     int64_t pts;
 
     if (s->flushing) {
@@ -588,17 +590,19 @@  int ff_mediacodec_dec_send(AVCodecContext *avctx, MediaCodecDecContext *s,
     }
 
     while (offset < pkt->size || (need_draining && !s->draining)) {
-
-        index = ff_AMediaCodec_dequeueInputBuffer(codec, input_dequeue_timeout_us);
-        if (ff_AMediaCodec_infoTryAgainLater(codec, index)) {
-            av_log(avctx, AV_LOG_TRACE, "No input buffer available, try again later\n");
-            break;
-        }
-
         if (index < 0) {
-            av_log(avctx, AV_LOG_ERROR, "Failed to dequeue input buffer (status=%zd)\n", index);
-            return AVERROR_EXTERNAL;
+            index = ff_AMediaCodec_dequeueInputBuffer(codec, input_dequeue_timeout_us);
+            if (ff_AMediaCodec_infoTryAgainLater(codec, index)) {
+                av_log(avctx, AV_LOG_TRACE, "No input buffer available, try again later\n");
+                break;
+            }
+
+            if (index < 0) {
+                av_log(avctx, AV_LOG_ERROR, "Failed to dequeue input buffer (status=%zd)\n", index);
+                return AVERROR_EXTERNAL;
+            }
         }
+        s->current_input_buffer = -1;
 
         data = ff_AMediaCodec_getInputBuffer(codec, index, &size);
         if (!data) {
diff --git a/libavcodec/mediacodecdec_common.h b/libavcodec/mediacodecdec_common.h
index 023d4c5fa7..0b21129fee 100644
--- a/libavcodec/mediacodecdec_common.h
+++ b/libavcodec/mediacodecdec_common.h
@@ -65,6 +65,7 @@  typedef struct MediaCodecDecContext {
     int display_height;
 
     uint64_t output_buffer_count;
+    ssize_t current_input_buffer;
 
     bool delay_flush;
     atomic_int serial;
@@ -78,7 +79,8 @@  int ff_mediacodec_dec_init(AVCodecContext *avctx,
 
 int ff_mediacodec_dec_send(AVCodecContext *avctx,
                            MediaCodecDecContext *s,
-                           AVPacket *pkt);
+                           AVPacket *pkt,
+                           bool wait);
 
 int ff_mediacodec_dec_receive(AVCodecContext *avctx,
                               MediaCodecDecContext *s,