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[FFmpeg-devel,5/7] avcodec/mediacodecenc: remove the strategy to create DTS

Message ID tencent_E2E9936B95CC490CEEB505497300C8539305@qq.com
State New
Headers show
Series [FFmpeg-devel,1/7] avcodec/mediacodecenc: add bitrate_mode option | expand

Checks

Context Check Description
andriy/configure_x86 warning Failed to apply patch
yinshiyou/configure_loongarch64 warning Failed to apply patch

Commit Message

zhilizhao(赵志立) Dec. 4, 2022, 5:12 p.m. UTC
From: Zhao Zhili <zhilizhao@tencent.com>

Use input PTS as DTS has multiple problems:
1. If there is no reordering, it's better to just use the output
PTS as DTS, since encoder may change the timestamp value (do it
on purpose or rounding error).

2. If there is reordering, input PTS should be shift a few frames
as DTS to satisfy the requirement of PTS >= DTS. I can't find a
reliable way to determine how many frames to be shift. For example,
we don't known if the encoder use hierarchical B frames. The
max_num_reorder_frames can be get from VUI, but VUI is optional.

3. Encoder dropping frames makes the case worse. Android has an
BITRATE_MODE_CBR_FD option to allow it explicitly.
---
 libavcodec/mediacodecenc.c | 28 +---------------------------
 1 file changed, 1 insertion(+), 27 deletions(-)
diff mbox series

Patch

diff --git a/libavcodec/mediacodecenc.c b/libavcodec/mediacodecenc.c
index dce4a96d1f..4b0397d1ea 100644
--- a/libavcodec/mediacodecenc.c
+++ b/libavcodec/mediacodecenc.c
@@ -64,18 +64,6 @@  typedef struct MediaCodecEncContext {
 
     uint8_t *extradata;
     int extradata_size;
-
-    // Since MediaCodec doesn't output DTS, use a timestamp queue to save pts
-    // of AVFrame and generate DTS for AVPacket.
-    //
-    // This doesn't work when use Surface as input, in that case frames can be
-    // sent to encoder without our notice. One exception is frames come from
-    // our MediaCodec decoder wrapper, since we can control it's render by
-    // av_mediacodec_release_buffer.
-    int64_t timestamps[32];
-    int ts_head;
-    int ts_tail;
-
     int eof_sent;
 
     AVFrame *frame;
@@ -368,11 +356,6 @@  static int mediacodec_receive(AVCodecContext *avctx,
     }
     memcpy(pkt->data + extradata_size, out_buf + out_info.offset, out_info.size);
     pkt->pts = av_rescale_q(out_info.presentationTimeUs, AV_TIME_BASE_Q, avctx->time_base);
-    if (s->ts_tail != s->ts_head) {
-        pkt->dts = s->timestamps[s->ts_tail];
-        s->ts_tail = (s->ts_tail + 1) % FF_ARRAY_ELEMS(s->timestamps);
-    }
-
     if (out_info.flags & ff_AMediaCodec_getBufferFlagKeyFrame(codec))
         pkt->flags |= AV_PKT_FLAG_KEY;
     ret = 0;
@@ -437,14 +420,8 @@  static int mediacodec_send(AVCodecContext *avctx,
             return ff_AMediaCodec_signalEndOfInputStream(codec);
         }
 
-
-        if (frame->data[3]) {
-            pts = av_rescale_q(frame->pts, avctx->time_base, AV_TIME_BASE_Q);
-            s->timestamps[s->ts_head] = frame->pts;
-            s->ts_head = (s->ts_head + 1) % FF_ARRAY_ELEMS(s->timestamps);
-
+        if (frame->data[3])
             av_mediacodec_release_buffer((AVMediaCodecBuffer *)frame->data[3], 1);
-        }
         return 0;
     }
 
@@ -463,9 +440,6 @@  static int mediacodec_send(AVCodecContext *avctx,
         copy_frame_to_buffer(avctx, frame, input_buf, input_size);
 
         pts = av_rescale_q(frame->pts, avctx->time_base, AV_TIME_BASE_Q);
-
-        s->timestamps[s->ts_head] = frame->pts;
-        s->ts_head = (s->ts_head + 1) % FF_ARRAY_ELEMS(s->timestamps);
     } else {
         flags |= ff_AMediaCodec_getBufferFlagEndOfStream(codec);
         s->eof_sent = 1;