for(int i = 0; i<120;i++)
{
    AVPacket pkt;
    av_init_packet(&pkt);
    ret = av_read_frame(inputFormatCtx, &pkt);

    pkt.pts = pkt.dts = i;
    pkt.pts = av_rescale_q(pkt.pts, inputStream->time_base, outputStream->time_base);
    pkt.dts = av_rescale_q(pkt.dts, inputStream->time_base, outputStream->time_base);

    ret = av_interleaved_write_frame(outputFormatCtx, &pkt);
    av_packet_unref(&pkt);
}
ret = av_write_trailer(outputFormatCtx);

for(int i = 0; i<120;i++){
AVPacket pkt;
av_init_packet(&pkt);
ret = av_read_frame(inputFormatCtx, &pkt);
packets.push_back(pkt);
}

vector<AVPacket>::reverse_iterator it;
int j = 0;
for(it = packets.rbegin(); it != packets.rend(); it++){
    AVPacket n = (*it);
    n.pts = n.dts = j;
    j++;
    n.pts = av_rescale_q(n.pts, inputStream->time_base, outputStream->time_base);
    n.dts = av_rescale_q(n.dts, inputStream->time_base, outputStream->time_base);
    ret = av_interleaved_write_frame(outputFormatCtx, &n);
    av_packet_unref(&n);
}

ret = av_write_trailer(outputFormatCtx);

[FRAME]
media_type=video
stream_index=0
key_frame=1
pkt_pts=0
pkt_pts_time=0.000000
pkt_dts=0
pkt_dts_time=0.000000
best_effort_timestamp=0
best_effort_timestamp_time=0.000000
pkt_duration=512
pkt_duration_time=0.033333
pkt_pos=48
pkt_size=12974
width=1920
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=N/A
pict_type=I
coded_picture_number=0
display_picture_number=0
interlaced_frame=0
top_field_first=0
repeat_pict=0
[/FRAME]
[FRAME]
media_type=video
stream_index=0
key_frame=0
pkt_pts=512
pkt_pts_time=0.033333
pkt_dts=512
pkt_dts_time=0.033333
best_effort_timestamp=512
best_effort_timestamp_time=0.033333
pkt_duration=512
pkt_duration_time=0.033333
pkt_pos=13022
pkt_size=473
width=1920
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=N/A
pict_type=P
coded_picture_number=1
display_picture_number=0
interlaced_frame=0
top_field_first=0
repeat_pict=0
[/FRAME]
[FRAME]
media_type=video
stream_index=0
key_frame=0
pkt_pts=1024
pkt_pts_time=0.066667
pkt_dts=1024
pkt_dts_time=0.066667
best_effort_timestamp=1024
best_effort_timestamp_time=0.066667
pkt_duration=512
pkt_duration_time=0.033333
pkt_pos=13495
pkt_size=511
width=1920
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=N/A
pict_type=P
coded_picture_number=2
display_picture_number=0
interlaced_frame=0
top_field_first=0
repeat_pict=0
[/FRAME]

[FRAME]
media_type=video
stream_index=0
key_frame=1
pkt_pts=14848
pkt_pts_time=0.966667
pkt_dts=14848
pkt_dts_time=0.966667
best_effort_timestamp=14848
best_effort_timestamp_time=0.966667
pkt_duration=512
pkt_duration_time=0.033333
pkt_pos=757791
pkt_size=65625
width=1920
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=N/A
pict_type=I
coded_picture_number=58
display_picture_number=0
interlaced_frame=0
top_field_first=0
repeat_pict=0
[/FRAME]
[FRAME]
media_type=video
stream_index=0
key_frame=0
pkt_pts=15360
pkt_pts_time=1.000000
pkt_dts=15360
pkt_dts_time=1.000000
best_effort_timestamp=15360
best_effort_timestamp_time=1.000000
pkt_duration=512
pkt_duration_time=0.033333
pkt_pos=823416
pkt_size=29642
width=1920
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=N/A
pict_type=P
coded_picture_number=60
display_picture_number=0
interlaced_frame=0
top_field_first=0
repeat_pict=0
[/FRAME]
[FRAME]
media_type=video
stream_index=0
key_frame=1
pkt_pts=30208
pkt_pts_time=1.966667
pkt_dts=30208
pkt_dts_time=1.966667
best_effort_timestamp=30208
best_effort_timestamp_time=1.966667
pkt_duration=512
pkt_duration_time=0.033333
pkt_pos=1546454
pkt_size=66021
width=1920
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=N/A
pict_type=I
coded_picture_number=117
display_picture_number=0
interlaced_frame=0
top_field_first=0
repeat_pict=0
[/FRAME]